Hello Lutz,
i can confirm this with my Samsung S6lite tablet (Android 10) with both Chrome and Brave browsers (well, they use the same engine so that's no big surprise).
That said, unfortunately i have no idea what is causing this.
What's really weird is that some buttons like the fullscreen toggle work without problems.
The zoom bar also "kind of" works when you push and drag the indicator but clicking the buttons doesn't. Very strange.
Any ideas from someone else, maybe??
cheers, Frank