My unlocked Note 10+ is still on Android 9 and One UI version 1.5. Every time I try to update it say the software is up to date also the security patch is from Oct 1st 2019. I bought the phone from Samsung website.
I had a similar experience with my N10+ it was stuck on the February 2021 for some months. I got fed up and did some research and found out about flashing via Odin.