Noticed in the Audio and Video blocks.
When clicking on the "Edit" button in the block toolbar, the button disappears. Depending on the interaction mode (mouse, keyboard) I've noticed different behaviors that I wasn't able to reproduce consistently. Also, not sure if there's a difference between Gutenberg in core (WordPress 5.3-alpha) or the plugin (currently 5.8.0).
Anyways, then the button disappears:
At this point, the "Edit" button re-appears, sometimes in the same location and sometimes... at the beginning of the toolbar. Couldn't reproduce consistently.
To clarify, I made two animated GIFs. To reproduce, sometimes the disappearing doesn't happen the first time "Edit" is clicked, so try multiple times.
Gutenberg version included in wp trunk 5.3:

Gutenberg plugin 5.8.0:

@draganescu hi! Do I recall correctly you fixed this?
Hi @afercia it is work in progress. I've been away for the past 2 weeks. I am working on implementing a component that should replace / refactor this whole edit flow thing on all the affected components here:
Thanks @draganescu !
This reminds me of #15641.
We now use the MediaReplaceFlow component in all media related blocks. See #19162