It does sound frustrating for sure.
Let’s try something else.
By looking at the pictures it looks like you don’t have any air intake control on your skimmer, but one thing comes to mind, try to get a restrictor for the air intake line.
I know, it sounds counterproductive however sometimes skimmers have larger pumps then needed in order to satisfy nova day’s market demands for more air intake.
Bubble Blaster 3000 pulls 1200-1400L of air per hour, if skimmer contact chamber is too small it will not produce stable foaming. Also you may want to try to stabilize foam by
inserting a tight ball of plastic netting inside the skimmer it will
not reduce water flow through but will brake larger bubbles in to smaller ones as well as reduce turbulence.
The finer the adjustments the better in terms of air control valve.
So back to air control: Try restricting the air flow it might make it more stable. It will also make bubbles smaller and foam denser. It will also make the pump to push more water through the skimmer so prepare for higher level or remove skimmer waste collection cup and then adjust. If pump will stay stable then with finer bubbles you will get better skimmate.
Nevertheless if pump is fine after power down and then fluctuates again it is indeed sounds like a malfunction.