Set

android {
   defaultConfig {
     vectorDrawables.useSupportLibrary = true
    }
 }

in your build.gradle

I think you need to update your dependencies

I got it to work while using those dependencies:

implementation 'androidx.appcompat:appcompat:1.2.0-alpha02'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation "com.google.android.material:material:1.1.0"


<com.google.android.material.floatingactionbutton.FloatingActionButton
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_src="@drawable/drawable_test"
    />

I know it’s old question, and others might have the same problem, so I add this answer.

As others suggested, add the following dependencies to build.gradle:

implementation 'androidx.appcompat:appcompat'
implementation 'com.google.android.material:material:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta4'

Also as others suggested, add this to build.gradle:

android {
   defaultConfig {
     vectorDrawables.useSupportLibrary = true
    }
 }

In the vector, change android:width and android:height to android:width="24dp" and android:height="24dp".

In layout, in com.google.android.material.floatingactionbutton.FloatingActionButton, add app:fabCustomSize="56dp" or instead of this, add app:fabSize="normal".

The FloatingActionButton widget provides a complete implementation of Material Design’s floating action button component.

upgrade your dependencies

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'com.google.android.material:material:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'

Using AppCompat and app:srcCompat is the most foolproof method of
integrating vector drawables into your app.

Finally

 <com.google.android.material.floatingactionbutton.FloatingActionButton
      app_srcCompat="@drawable/your_vector"

Note – Kindly reduce width,height value.

   <vector xmlns_android="http://schemas.android.com/apk/res/android"
    android_width="20dp"
    android_height="20dp"
    android_viewportWidth="200"
    android_viewportHeight="200">

Android Studio 1.4 introduced limited compatibility support for vector
drawables by generating PNG files at build time. However, the vector
drawable and animated vector drawable support Libraries offer both
flexibility and broad compatibility — it’s a support library, so you
can use it with all Android platform versions back to Android 2.1 (API
level 7+). To configure your app to use vector support libraries, add
the vectorDrawables element to your build.gradle file in the app
module.

Use the following code snippet to configure the vectorDrawables element:

//For Gradle Plugin 2.0+
 android {
   defaultConfig {
     vectorDrawables.useSupportLibrary = true
    }
 }

u can solve your issue with this idea,

<com.google.android.material.floatingactionbutton.FloatingActionButton
    android_id="@+id/fab_new_sale"
    android_layout_width="wrap_content"
    android_layout_height="wrap_content"
    android_layout_margin="16dp"
    android_layout_marginEnd="16dp"
    android_layout_marginBottom="16dp"
    app_backgroundTint="@color/colorAccent"
    app_layout_constraintBottom_toBottomOf="parent"
    app_layout_constraintEnd_toEndOf="parent"
    android_src="@drawable/ic_cart_plus"
    android_scaleType="center"/>

here u can use android:src insted of app:srcCompat

It worked for me using the following depencencies

implementation 'androidx.appcompat:appcompat'
implementation 'com.google.android.material:material:1.1.0'
implementation "androidx.constraintlayout:constraintlayout:2.0.0-beta4"

try updating these depencencies. I didnt have to do any rescaling. maybe also refer to this and this questions as it might be that your drawable is just not centered properly and leaving the circle

You just need to change your srcCompat to src, and that would solve the problem for you.
I am attaching my own FAB code for your ease:

<com.google.android.material.floatingactionbutton.FloatingActionButton
        android_id="@+id/fab_explore"
        android_layout_width="wrap_content"
        android_layout_height="wrap_content"
        android_layout_margin="@dimen/dp_16"
        android_src="@drawable/ic_explore_black_24dp"
        app_backgroundTint="@color/accent"
        app_tint="@color/color_white"
        app_layout_constraintEnd_toEndOf="parent"
        app_layout_constraintBottom_toBottomOf="parent" />

I’m trying to setup a vector asset into a fab. But the result is like this:

As you can see the vector is there but way down and to the left. here is the layout

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns_android="http://schemas.android.com/apk/res/android"
    xmlns_app="http://schemas.android.com/apk/res-auto"
    xmlns_tools="http://schemas.android.com/tools"
    android_layout_width="match_parent"
    android_layout_height="match_parent"
    android_background="@color/colorBg"
    tools_context=".ui.main.fragments.HomeFragment">


    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android_id="@+id/fab_new_sale"
        android_layout_width="wrap_content"
        android_layout_height="wrap_content"
        android_layout_margin="16dp"
        android_layout_marginEnd="16dp"
        android_layout_marginBottom="16dp"
        app_backgroundTint="@color/colorAccent"
        app_layout_constraintBottom_toBottomOf="parent"
        app_layout_constraintEnd_toEndOf="parent"
        app_srcCompat="@drawable/ic_cart_plus"
        android_scaleType="center"/>

    <androidx.recyclerview.widget.RecyclerView
        android_id="@+id/rv_home_cards"
        android_layout_width="0dp"
        android_layout_height="0dp"
        android_foregroundGravity="center_vertical|center"
        app_layout_constraintBottom_toBottomOf="parent"
        app_layout_constraintEnd_toEndOf="parent"
        app_layout_constraintStart_toStartOf="parent"
        app_layout_constraintTop_toTopOf="parent" />


</androidx.constraintlayout.widget.ConstraintLayout>

And heres is the vector:

<vector xmlns_android="http://schemas.android.com/apk/res/android"
    android_width="200dp"
    android_height="200dp"
    android_viewportWidth="200"
    android_viewportHeight="200">
    <path
        android_fillColor="#FF000000"
        android_pathData="M165.1,119.28L75,119.28l2,9.84h82.48a7.37,7.37 0,0 1,7.19 9l-1.7,7.46a17.2,17.2 0,1 1,-19.54 3.19L81,148.77a17.21,17.21 0,1 1,-20.6 -2.63L38.85,40.62L17.38,40.62A7.38,7.38 0,0 1,10 33.24L10,28.33A7.37,7.37 0,0 1,17.38 21h31.5a7.38,7.38 0,0 1,7.23 5.9l2.81,13.77h120.7a7.37,7.37 0,0 1,7.19 9l-14.52,63.91A7.38,7.38 0,0 1,165.1 119.28ZM135.38,72.58L120.63,72.58L120.63,60.28a4.92,4.92 0,0 0,-4.92 -4.91h-4.92a4.91,4.91 0,0 0,-4.91 4.91v12.3L91.13,72.58a4.91,4.91 0,0 0,-4.92 4.91v4.92a4.92,4.92 0,0 0,4.92 4.92h14.75L105.88,99.62a4.91,4.91 0,0 0,4.91 4.91h4.92a4.92,4.92 0,0 0,4.92 -4.91L120.63,87.33h14.75a4.92,4.92 0,0 0,4.91 -4.92L140.29,77.49A4.91,4.91 0,0 0,135.38 72.58Z" />
</vector>

I will appreciate any help with this issue