Up to date Safari running on new computer still tells me unsupported browser in certain web pages

Just purchased a new MacBook Air M1. Runs great! Figured I'd try to use Safari since I had been unsuccessfully using it in the past because I was always getting "this browser is unsupported, try updated to the latest version of Safari." I am always updated to the latest version. So, I just used Chrome instead. Fast forward to yesterday, got my new mac up and running and updated to the latest versions of everything AND I still get this error message. I tried to open my icloud and I got that message on Safari; it works just fine on Chrome. I migrated everything from my old laptop to this new one so I'm assuming the issue lies somewhere in the system. This is not a serious issue as Chrome works just fine, but I'd like to be able to use Safari again. It used to work well years ago, I must have updated to some new system software at some point and lost the ability to use it...idk.