I’m now hunting bugs in Catalina, to build my usual incomplete list for publication here. You’ll be delighted to know that one which still isn’t fixed is the Finder’s incorrect column width bug, which goes back to Mavericks and earlier, as described here. That bug is now so old that it’s a definite feature, and continues to annoy me every day.
One peculiar bug which I have now come across in two quite different apps results in their displaying some or all of the contents of windows upside down and in mirror-writing, as shown below.
The example here is the excellent but unsupported newsreader Pulp, but I have also had it reported in an older version of Microsoft Word 16. In the latter case, this is fixed simply by updating the app to a newer version which is fully compatible.
As this is confined to a small number of individual apps, this is most likely reflects issues in their display of window contents, rather than a bug in Catalina as such.
A few users have suggested switching to Light Mode, or disabling Reduce transparency in the Display item in the Accessibility pane. Nothing that I have tried has had any effect on Pulp. Although that app is 64-bit, delivered from the App Store, and should be fully compatible with Catalina, unless you’re good at reading upside-down mirror-writing, this can’t be fixed, and is the death knell for that app. I have therefore replaced Pulp with Reeder 4 as my newsreader.
I’d be interested to know if you’ve come across this problem in any other apps, please, particularly if you’ve found a solution.