Myotis is a genus of bats from the smooth-nosed family that is found all over the world.
Myotis is the largest genus of bats with more than 100 species.

During our stay at Gasthaus Moosegg in the Pfänder Mountains, a bat flew into our room one night and, after having flown several laps around the room, sat next to the mirror.
Fortunately, after about 20 minutes, it flew out of the window again.

I asked the Bat Protection and Research Organization in Austria (KFFÖ) if they had any idea what kind of bat it was.
Dr. Guido Reiter, a bat expert working at the University of Vienna and chairman of the KFFÖ, has informed me that it is very likely to be the Whiskered Bat (Myotis mystacinus) or the Brandt's Bat (Myotis brandtii).
It is impossible to determine from the photos which species it is exactly.

Pfänder Mountain, Bregenz, Vorarlberg, Austria, 2 August 2020