Ah yes, the flying racecar that is the Mercedes-Benz CLR. For context, this car went flying and did a backflip during it's race debut at the 1999 24 Hours of Le Mans - prompting Mercedes to withdraw all their cars from the race as there were TWO prior flights during qualifying and practice as well. Video of the flip from during the race.
After such a disastrous debut the car was shelved and never hit the track again, and the LMGTP ruleset it was built for was also canceled. Between this and the 1955 tragedy, it's no surprise Mercedes doesn't seem to have any interest in joining Hypercar or WEC in general.