Apologies if this has already been reported.
Starting with Anki version 2.1.50, the answer button frame at the bottom of the review window is overflowing, causing scrollbars to appear.
I’m running Arch Linux with the i3 window manager. My copy of Anki is built from the “anki-bin” package from the arch user repository.
This overflow occurs even on a fresh instance of Anki without any addons installed.
Please let me know if there’s any extra debug or diagnostic logs I can provide to help.