Hi,

I used to have Raspberry Pi 4 and the next list of equipment (all connected through USB):

- Canon 250D
- QHY 5L-II-M
- ZWO EAF
- iOptron mount

All worked just fine. Recently I upgraded Canon EOS 250D against QHY5III715C. Stellarmate recognises it, but then evil "magic" happens:
- when I move ZWO EAF, QHY715 immediately fails to take shots (but after disconnect/connect in INDI panel OK)
- if I try to use QHY 5L-II-M for focusing, this time mount disconnects.
- also were cases when exposition on QHY715C starts, but hangs just before downloading.

I believe it is due to insufficient USB power and I need to buy a powered hub, what do you think? Any other suggestions?

I would bet that yes, this is due to insufficient power.

Seems like insufficient power.
Also, check if the USB cables are connected correctly.