S21 + 5G Oneui 7.0

The carrier is responsible for Samsung Software Updates 
Ref Link: https://us.community.samsung.com/t5/Galaxy-S22/Explanation-on-what-does-the-carrier-has-to-do-with-phone/td-p/2723401
Xfinitymobile is the carrier.
These updates (e.g. firmware) have security patches.
Not having these makes a phone vulnerable.
I did not receive ui 5.0 or 6.0.
Not having any details related to when a past due vulnerable phone will get patched, as the one pushing the patches is not an answer.

@user_sqaszw that is correct, the manufacturer sends the updates over to us to be pushed. Typically, the device should tell you when updates are available. Have you checked here to see if anything is available: https://www.xfinity.com/support/mobile/device-troubleshooting?page=topic/software/check-for-install-software-update/device ? 

All samsung operating system updates are performed 3 ways.
1. Side loading - Not recommended
2. Samsung Members (Beta Program) - Join a beta program and get the updates directly from the manufacturer. 
3. Through your provider

I wouldn't do 1. The program for 2 was closed for UI7. UI8+ I believe will not support S21 as it is EOL 2026 for security updates.. so I cannot sign up for Samsung Beta 8.
For 3 when I click check updates on my phone, it says up to date.. the last update was Feb 6th, 2023 as stated above and my UI is 4.1.
Outside of clicking check for updates inside my phone there is nothing I can do nor troubleshoot.
I decided to circumvent the issue by switching my phone to apple so updates from this point forward are pushed by the manufacturer.
This was not resolved, but it can be closed as I no longer will use the phone with the issue going forward.