Returning for a moment to the note that sudo should not be used with pamac…
If you installed Steam and related packages using pamac – and used sudo when doing that – it may have contributed to Steam not working. Specifically, expected permissions might differ as a result.
There are potentially other reasons; I can only think of a few that haven’t already been addressed.
Is any Steam Library on a foreign filesystem; like NTFS, for example?
Screenshots are generally discouraged as they are not searchable and usually add nothing that a simple comment cannot express. Also, as they accumulate over time, they are not friendly to server performance.
This means the beginning or end of a partition isn’t properly aligned to the expected (1 MB) boundaries. This seems to happen sometimes after using Calamares to automatically create and format partitions during install.
If /dev/sda2 is your / (root) partition this could be reason for concern – if the misalignment was at the beginning of the partition. In this case it’s not; the misalignment seems to be at the end of the partition; and although it’s correctable, I’d suggest ignoring it.
There is also this note from Known issues and solutions in the 2024-10-10 update announcement:
Cheers.