It looks like Xcode 13.2 and macOS 12.1 are now available (for me at least).

I'm also experiencing the same error with my workflows today.

I'm also running into this issue as of today.

I've also been running into this issue when building my app with Xcode 13.3. One workaround I have found to work is setting the UISplitViewController's style to ‘Unspecified (Discouraged)’. Alternatively the issue does not seem to appear when using Xcode 13.2. I have submitted a feedback with a minimal reproducible project #FB9959996