Found 3 neutrals for other circuits landed in another subpanel - subpanel breaker tripping

Found 3 neutrals for other circuits landed in ansul system subpanel - subpanel main breaker tripping. Going to correct this but wondering if that is tripping the main breaker feeding the subpanel.
It is a shunt trip breaker and a ansul system subpanel for everything under the hood.
This is a new breaker we just replaced but still have the same issue.
I figured this out when I went to land the neutral better so the cover wasn't pressing on it with the subpanel ansul breaker off. Lots of sparks and 15 amps on the neutral. It seems they figured out the hood fans should not be killed by the shunt and ran power to them from the main panel but kept the neutrals and grounds in there. (120v hood fans). The ansul system control power was also wired the same.
So, what I am wondering is if this could cause random shunt (subpanel feed breaker) to trip randomly. It has worked for some time (3 years?). The other panel is 1 foot away.
Not safe, but can't figure out what is tripping the 100a shunt breaker when it only has 35amps on it under full load. This happens 6 times a day or not at all. Never get the same info as to what might have tripped it. One person actually told me only half of the stuff under the hood was turning off at first which would be very unlikely. Nothing appears to be backfeeding that panel.
Any thoughts aside from the obvious bad wiring practice? I did not rewire it because my guys can do that and I keep minimal supplies on my truck.
I just can't help but wonder if the additional neutral load is causing some kind of electrical voodoo.
 
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