Sync issue with deleting messages

I have a 2014 era MacBook that can only run up to Big Sur (11.7.9). The sync will work if I delete text messages from my iphone, but will not work if I delete from the MacBook. I've tried pretty much everything in the message and iCloud settings to no avail, up to re-installing the OS, including help from an Apple support tech. BTW, she was quite helpful and I was surprised to be able to talk over the phone with her. Rare these days.

Is this a known issue, and something I can't really fix?

It's probably easier to delete from the phone or iPad anyway, since I can't delete multiple messages from the older Mac running Big Sur (as I found out from another question I asked in the community forum).