To those who uses a carrier powered by T-mobile such as Walmart family mobile and metro or any carrier or pre-paid that uses tmobile services also known as "Un-Carrier" just know you are not forgotten. Tmobile is working very closely to release the Android 12 update to the rest of the unlocked samsung galaxy s21 series among other phones.
Here is the source link:
Try installing Google carrier services and then reboot your phone and then open the settings and check for the update, please backup your data before you upgrade
Still no luck, I uninstall and reinstalled Google carrier services and turned off my phone waited a few minutes and rebooted and still no luck, I think Un-Carrier sim cards get different treatment after primary carrier customers gets theirs.
I've noticed, but I believe those are customers using full plan or pre-paid services of tmobile directly, I however went with a cheaper plan with Walmart family mobile that depends and uses tmobile services, and I haven't received the update, but thankfully I read today that they are working on it, I just hope it's sooner if not I don't mind waiting, I just wanted to spread the word those using those kinds of services are not forgotten.