Problem with Mail Flag Colors

Has anyone had an issue with the colored flags in Apple's mail client with Big Sur? For my business, I use various flag colors to denote things like priority and how long I plan to keep an email. Yesterday, I was flagging a few emails on my iPad, and noticed a bit later that a flag I made blue had turned back to red. I went on my iMac and discovered that hundreds of emails all had their flags changed from some color to red. Well I'm ******. Probably way too much work to fix it back on each email. Don't know if the problem was caused by a bug on the iPad, iMac or iCloud Or if I have a faulty expectation that if I set a flag color on an email, that it should remain that color. I just wish that roll out of operating system and app updates didn't destroy stuff that had previously worked.