The internal leak looks to be coming from the pressure relief valve pipe that goes through the wall to the outside. The filling loop is currently connected.
I have a Vaillant TURBOmax VUW 242/1 e, 282/1 E and white hand on the lower scale of the pressure and temperature gauge is at 2.2 bar. According to the manual, it should be between 1 and 1.5 bar.
I can see that there is a slow leak coming from one to the copper pipes and also a slow leak...