I got it back to working somehow, the glitch was gone after one update (if I remember correctly, this was in 1.10.x). Probably something was wrong with my game files, since I have been messing around with that a bit...
Hello,
I found a glitch that makes my crafts' textures glitch out and can get really annoying.
It is happening when you have a fairing part on your craft and you undo a move. Images can be found in the reddit post I linked down below.
This texture change only affects cargo bays (I only tested Mk3 Medium and Long ones) and Vector Engines. It replaces parts of the Texture (Cargo bay main part and the Combustion Chamber of the Vector Engine). Once you have that part placed and you undo a move the texture gets replaced by the Fairing Texture (if you chose a fairing design, this will get applied too).
Thanks for help.
Detailed explanation with images can be found here: https://www.reddit.com/r/KerbalSpaceProgram/comments/j09mof/glitch_broken_fairing_textures/