I noticed I could not restore pg dumps as expected when migrating to a new server. I had to add some parameter to pg dump so it's a better/more neutral dump or something, which was easier/able to restore. So - definitely check your backups.

Trying the restore locally is also an option. Just to verify it works and the expected data is there.

How important it is to verify and verify regularly depends on how much loss you're willing to accept.

Once verified, as long as you don't do big version upgrades or automation changes, I would expect it to continue to work indefinitely. A semi regular verification still makes sense, though.

At work I know my DB backups definitely work for other reasons, due to regular restores in non-prod.

For side projects I definitely recommend verifying it at least once, when setting up automated backups/scripts for backup creation.