@CHMultimedia could help you about this if you give him the exact model of your phone but we'd like to know WHY you want to downgrade...
I think only Note10 series have received ONE UI2.1 (i got one) and personnaly i would'nt downgrade mine, we have a lot of unbeleivable new features from the S20 series and i like it a lot...
The bootloader is locked for some devices and the "OEM UNLOCKING" setting in the developer options mode is controlled/dictated by Google/Android. Samsung has no control over what is removed or added to the OS. If the Boot loader is unlocked then Samsung doesn't recommend it as you will not receive any security updates which is the most important part, the performance of the device degrades.
Uh, no. Samsung allows for bootloader unlocking on their tablets and their phones outside of Canada and USA. Even the tablet I'm currently using allows this. And most Android OEMs, including Google themselves, allow users to unlock the bootloader. Samsung has full control and @Steve01 said himself that Samsung Canada took the decision not to allow users the right to do as they please with their own devices. And where did you read it would affect device performance? Because that's news to me and everyone at XDA-Developers.
Google had nothing to do with Samsung's decision to Lock the Bootloaders on Snapdragon devices sold in North America! I suspect that the North American Carriers put pressure on Samsung to Lock the Bootloaders & the Carriers are Samsung's biggest customers.
As for Security Updates - Doesn't matter if you did Unlock the Bootloader or even Root the device - You can still Flash the Stock Samsung Firmware with Odin...
If you have a Note10/+, you can absolutely rollback to OneUI 2.0 if you installed OneUI 2.1. I'll just need to find the firmware files. Please confirm if you have a SM-N970W or a SM-N975W? You may find this in Settings/About
Wow, I should probably start archiving firmwares lol. So many people ask for firmware help
