We are discussing at the company the migration of some on premises services to cloud alternatives. Is it market practice to backup servers on AWS, or repositories on GitLab.com, or files on Google Drive?
Personally I'm pretty confident on these big companies, I'm pretty sure that their backups will outlive mine 10 out of 10 times. But not backing up the company data may be a liability.
What is the best practice on this subject?
This is a question of fault tolerance vs backups.
Whilst your cloud service may be very fault tolerant in that it never goes down and needs to be rebuilt. That is not the same thing as backing up your data.
For example, say I execute some malicious sql which deletes or ammends rows in your database. The next day you notice the problem. But you can't recover unless you have a backup copy of the data.
Similarly there have been cases where cloud accounts have been hacked and servers and cloud backups deleted.
Companies have gone bust because they didnt have a backup copy of their data held in a different location.
So yes, regardless of how fault tolerant your data store is, you also need backups
