help need to undo catalina update

Refer to Revert your Mac to a previous macOS version - Apple Support.

Time Machine automatically creates a "local snapshot" prior to every macOS update. You do not have to explicitly create one. You only have to turn on Time Machine. To restore that local snapshot, select the Mac's startup disk in Step 4 of the above—not the Time Machine backup disk.

You should definitely back up your files, but if Time Machine was "off" and you are absolutely certain that you had no backup prior to installing the update, "undoing" it is not practicable. It would require completely erasing the Mac first, and upgrading Catalina to a version immediately preceding its most recent update may not be possible.

I'd start by addressing the problem at hand: what is "DDO", and what led you conclude a routine macOS update broke it?

It's nearly certain its developer is aware of the problem. If they don't have an update for their product already, they are probably working on one.

No worries. What's DDO?

If it's D&D Online its support forum doesn't appear to have any recent complaints. Try asking there: https://www.ddo.com/forums/forumdisplay.php/265-Mac-Technical-Assistance. Perhaps its client just needs an update.

Here you go: Back up your files with Time Machine on Mac

That sounds right. Try it.