14.3 release notes mentioned that they addressed the bug but no joy. As bug returned. 14.4 release notes make no mention of it at all.
For those asking about a rebuild, it's been done countless times by many users in this thread from a fresh IOS install via ITunes and then restored from the cloud. It'll correct the issue temporarily but the bug eventually returns.
For reference as that we're all on the same page, I'm only speaking about iMessage/SMS notifications and not any other app/service (WhatsApp, etc). Also, I don't have nor have I ever had any other Apple products (iPad, watch, MAC) other than my iPhones.
Continue to contact Apple via their feedback link as Apple engineers do not read these forums. These forums are for user discussions.
I'm running IOS 14.4 on my IPhone 12 Pro Max. First saw the bug when I installed IOS 14 on my IPhone-X.