Deleted iMessages routinely reappear. Why?

i have:

• 2018 intel mac mini
• iphone 12 pro max
• ipad mini gen 5
• apple watch 44mm, watchOS 10.6.1
• (all other device OS' are up to date as of today)

my recurring issue is that deleted imessages keep reappearing, seemingly at random. from my mac mini i often delete imessages and then i empty my recently deleted messges list. i used to also do the same from my phone but for some reason apple decided to remove the ability to select all when clearing recently deleted messages in ios 26 (why?).

so why does this keep happening? i suppose it seems related to having multiple devices and they each are out of sync with each other -vs- icloud and when they "sync" this happens. can apple not get a handle on maintaining proper sync across multiple devices which may not all be online and available all the time at the same time?

thanks.