Where has my custom workspace gone in PPro 25.0?

After upgrading to PPro 25.0 I lost my custom workspace and keyboard preferences. I spent quite a bit of time rebuilding it, saving it, saving changes to the workspace... No crashes or anything untoward.

Today I reopened PPro 25.0 and my custom workspace was gone. Any idea as to where PPro 25 might have saved it? And with what extension?

Thanks