[plqbfbv]

In Github it needs to be explicitly configured (Settings > General > Delete head branches after merging), Gitlab is the same.

A lot of my developer colleagues don't know how git works, so they have no idea that "I merged the PR" != "I deleted the feature branch". I once had to cleanup a couple repositories that had hundreds of branches spanning back 5+ years.

Nowadays I enforce it as the default project setting.