TL:DR; Can we backport version telegram-desktop 3.1.1+ds-1~bpo11+1 from bullseye backports to PureOS byzantium?
The reason for this is:
We had reports from users that telegram-desktop 2.6.1 version currently in Byzantium now shows a warning that the application is old and will soon be unsupported every time you open the application.
Besides this warning the application no longer lets users setup their accounts. More details about this problem is debated in this Debian mailinglist thread:
"Telegram recently updated their API introducing backward incompatible changes. Because of that a
version of the package currently in bullseye ceases to work."
There is also a bug report in Debian.
The telegram-desktop 3.1.1+ds-1~bpo11+1 version from debian bullseye-backports; does not have this issue, and from a test I was able to manually install it in PureOS and it worked out of the box with no dependency issues:
This affects both laptop/desktop users and Librem 5 users.