That is polyurethane foam. Its the other factory option to pick and pluck, soft, open cell and eventually disintegrates. The polyethylene foam is much better long term and for heavy objects.
Is it possible your reg pressure is below 120 bar/12mpa? Low pressure causes failure to fire, but sear is unlatched, so safety will not engage, any rise in pressure (warming up or filling) causes valve to complete firing cycle
Looks like a rubber piece (antivibration/loosening) that goes in the trigger adjusting screws in back of gun. Serrations are from screw threads. Could have jammed your trigger mechanism or allowed it to come out of adjustment. Call Kelly.
Are they opening the valve while filling? They are used to one way check valves on paintball tanks. Maybe a novice operator. Run compressor until output gauge reaches tank pressure, open tank knob, fill......etc
Huggett snipe is great, gold standard of mods in .22 and .25. I do have the huben moderator, smaller, lighter, lets you use iron sights, not as quiet as the Snipe. Mini Mgna is shorter than snipe but bigger diameter may even block a Red Dot.