It took me a while, comparing to a similar code that didn't show said behavior

I changed some code and the final change that nailed it referred to a form inside that component.

The wokring form is conditional using:

 <form [formGroup]="form" *ngIf="bShowSubmit">

while said form, with the animation on the button, is not:

<form [formGroup]="form">

Changing the statement to

<form [formGroup]="form" *ngIf="true">

disabled the animation.

WTF ?!

By quickly pressing print screen I was able to capture the button initial view: https://imgur.com/a/zYSXSp6

Final state, less than a second away: https://imgur.com/a/oWxVKIB

It is very persistent, always happens when changing views

Tried to reproduce this problem on my end but without success. I added the button to the body of the element with mdbCollapse directive, just like you mentioned.

The normal button doesn't have any animation. If you mean that button 'animates' from 0 to full height then it's expected behavior caused by the collapse animation.

If the problem is related to something else please provide more details (full code, reproduction steps). A screenshot / gif would be nice in this case too.

Update:

Changing

  <div mdbCollapse [isCollapsed]="false" #box="bs-collapse">

to

<div>

doesn't change