The VSC usually are wider apart (60 - 80 KHz) and can be very strong - if you zoom in, and look closely, you may get more of a clue.
A switcher will show a fuzzy set of carriers when you zoom in and they will drift...
The VSC's I've seen have 60 Hz carriers when you zoom in and are very stable.
VSCs are used as energy savers on pool and well pumps.
Although its fun to speculate about waterfall signatures on RFI, the only real solution is to hunt them down and isolate the offending source.
Good luck! These things can be really annoying!
I would like to put the radio on a battery, connect my laptop, and cut off the power to the house and the UPS-es, then turn each circuit individually until I catalog the birdies that I am creating. Some of them do seem to slowly creep along the panadapter, so they are not necessarily at fixed locations. If you zoom out you will see that they are stronger at one point and fade out toward the ends.
You are lucky! My VFD (variable frequency drive), which seems to be the earlier name for VSC, was so strong it was s9+20 on 40M and wiped out the airport beacon at 350Khz. It took two line filters, hammond electrical shielding box, shielded 3 phase wiring, and an isolated ground. It was only a 1HP motor.
Just happened my entire back yard lighting wiring (aka long wire antenna) was on the same circuit.