Charging FP5 on and off

Hello!
I’ve got a new FP5, very happy with it overall.

It seems to be charging just fine with different cables and plugs, but I connected it via USB-C to a Dell docking station and it’s charging on and of every few seconds. It’s mainly noticeable because it vibrates when connected to power, so it keeps doing that every few seconds as well.

Tried different cables, checked all of them for defects / dirt, could it be because of the power source / docking station?

I’ve seen that randomly, too, with the WD19TB at my work. My impression is that the USB-C socket in the docking station is a little bit odd, I can make it connect and disconnect by gently moving the plug left and right (there’s some play in there). If I don’t move it, however, the charging is stable. I use slow charging only, if that makes a difference.