Betta Fish: Fin Rot determination

I’d still consider myself pretty new when it comes to this kind of stuff. I’m not sure how to tell if a fish has fun rot or not but it kinda seems that way to me. Fully planted 20gal. Water conditions are right where they need to be. Super active and friendly fish and always up top by the glass when I am around. Gets along fantastic with the other fish in the tank and I have never once seen any of them nip in the 5 or so months of having him. Could be maybe getting cut from the log but I’m not sure. Thanks for the help.