That ‘NEVER’ option had been ticked long before your advice, but it is not wholly effective - i.e. the tag slips through in some instances
If the important tags sometimes still show, then sounds like “your Gmail mailbox end is the problem” and you need to “also setup to disable the important tag there as well” as I did prev.
“Disable important tags in Gmail online”
https://forum.emclient.com/t/i-disable-tag-important-from-gmail-ans-still-in-em-client/82897/4