Style guide currently says:

Featured artists should always be entered in the artist credit, not in the titles. You should generally enter the credit as it appears on the release, omitting any separators (like parentheses) that are intended to separate it from the track title. For example, if the tracklist has "Artist 1 - Song Name (featuring Artist 2)", enter "Song Name", by "Artist 1 featuring Artist 2".

However, if album uses "feat" i.e. the abbreviated version of "featuring" but without a period at the end, then I believe that we should add a period and not be literal about it.

Example of edit that uses "feat": https://musicbrainz.org/edit/48943499