Big Sur beta issues

The macOS Big Sur beta has been stable overall, but hasn’t been without issues for me on the 2017 iMac. I’m keeping a list here.

Emacs crashes on launch. I’m using emacs-plus. I’ve tried all the usual fixes but no luck.
TiddlyDesktop crashes on launch, which means I’m editing the wiki in Firefox for now
Chronosync won’t read it’s own sync files
Lightroom Classic works but is so slow that it’s unusable
Google Backup and Sync (used for Google Photos) crashes on launch
I can’t change my desktop background to the Big Sur default image (acknowledged in release notes)

Some of these are known issues. Some could be just me. Other than Emacs not launching in a GUI, I don’t regret installing the beta, yet.

Added later:

My menubar items are all white, making them hard to read in light mode. Had to switch to dark mode, which I dislike.