The issues I had (granted this was probably a decade ago), was that Gmail uses tags and IMAP uses folders. The translation there always felt messy and cumbersome. To me, this is why I felt Gmail wasn’t good in generic mail clients and really needed one built for Gmail.

Maybe all those apps have since updated to natively support all Gmail’s features, but that is also a cat and mouse game with all the stuff they try that doesn’t fit neatly into established mail protocols.