Bought these lights in early 2023, been using them for over 2 years. I've tried 4 of them for my Rockboard 4.2 (one arrived without the clear plastic and buttons over the light, Thomann fixed the issue immediately, excellent customer service).
Thing to note: all 4 of them were tight on the left side - the light stays put where it's set, and very loose on the right side - the light just falls down if it's not put straight up. At least it doesn't fall towards you on the board, there's a stopper for that. So I reckon that it has got to be a design problem, not a quality control problem. I switched both the lights, and their mounts around, and tried all 4 mounts on left and right side too and took a lot of time to test it out.
Another thing is that sliding them into traveling position isn't always easy and it may take some force as the light's power cable doesn't slide smoothly.
Otherwise they're a good product, still exactly the same as the day I got them. 4 different light intensity levels, 6 different colors. They're on my Rockboard 4.2 and that board goes in and gets out of the gigbag with lights attached just fine. Be sure to put the lights facing up when putting the board to its gigbag. As I play a lot in the dark these are invaluable, and if lost or broken, I would buy again despite the issues.