[Mastodon] User handles without instance names not recognized as such when replying to a post

[EricBrunel]

What happened?

Replying to a post usually automatically includes all the handles of users in the original post. However, this doesn't seem to work if a user handle is just @ followed by their user name, without @instance_name behind it. But this kind of user handle is valid: if the user is on the same Mastodon instance as the original poster, it can be referenced as just @user_name.

Expected behavior

All user handles in the original post should be automatically included in the reply, whether they're written as @user_name@instance_name or just @user_name.

How to reproduce

1. Spot a post in your feed that references a user with just @user_name, without their instance name.
2. Click on the "Reply" button: the name for the original poster is included, as well as all the user names that include an instance name, but not the referenced one that doesn't have an instance name.

What platform are you seeing the issue on?

None

Additional context

This seems to happen on all platforms. I could reproduce it in version "weekly 2024-00" of the Linux desktop client and in version "weekly 2024-01" of the Android app.