Searching for the "Mathias Bathe REMIX" of M83's "Solitude" does not yield an official or widely recognized release by an artist of that specific name. It is likely that this is an unofficial bootleg, a very recent upload, or a possible misidentification of one of the many popular reinterpretations of the track.
: A popular melodic house version played at major events like Brunch Barcelona . Solitude (Mathias Bathe REMIX) - M83
Since the specific Mathias Bathe remix is not appearing in major databases, you might find the version you're looking for among these popular reinterpretations: Searching for the "Mathias Bathe REMIX" of M83's
The most prominent versions and remixes of include: a very recent upload