Is there a backup or alternative realisation of working cryptocurrency mixer?

Now they will pivot to buidling a decentralized Github ;)

It was deleted? Is that a fact? The first sentence of the article says suspended.

What is the difference? They cannot use that account anymore.

A suspension preserves history, name etc. while rendering the account inaccessible. It's chmod 000 rather than rm. The sanctioned user can deal with the reason for the sanction and after that, recover the account, all the repos that weren't relevant to the sanction, and perhaps also the relevant repos.