When I start to type !casualeu the markdown autocomplete provides the following code:

[!casualeurope@piefed.social](https://piefed.social/c/casualeurope)

Example:

!casualeurope@piefed.social

This causes links to Piefed communities to open in the browser instead of in Voyager.

This format without markdown works for Lemmy, Mbin and Piefed communities:

!casualeurope@piefed.social

Example: !casualeurope@piefed.social

I usually strip away all the markdown after autocompletion, but it’s a little tedious.