The light seems to flash in concert with the gunshots. Just sayin’..
I would say it's not a muzzle blast, but a reflection of a muzzle blast from another location...Outside the hotel...
Where are the broken windows? Surely they don’t have self sealing windows that you can shoot through without them breaking.
Did the smoke/fire alarms show anything on the 4th floor?
It’s a strobe light either from inside the room or reflected off the mirrored glass. The flash pattern is too consistent.
Besides, from that low of a floor, they’d be shooting through the trees.