Is this mold?

Pictures

I was tasked to put a new wallpaper in a room of my parents house.

House was built in 1985, location is southern Germany. The wallpaper was last removed and changed around 2010 with no visible damage in that area.

The wallpaper only has that damage in one specific part of the room. The opposite side of the wall the wallpaper was on is the bathroom.

Wall, that the wallpaper was on, is dry to the touch. Though it is also slightly discolored.

The wooden bar is also slightly discolored, only in the area with the damaged wallpaper.

So... mold, or not? Also, if it is mold, do I need to get someone to check the pipes? The front of the wallpaper has been slightly discolored in the part of the room for 10+ years according to my dad (Great job not doing something sooner -.-), so if it's a burst pipe that's responsible, I feel like the damage over the past 10 years would have been way worse.