Shimano 105 r7000 shifter rattle?

Hello everyone.
On my last ride my right shifter started rattling with no apparent damage or change in functionality, nothing seems to be loose and the shifter and brake lever works perfectly.

It was driving me nuts so I took a closer look and It seems like something broke but I can't tell what it is. Looks like a washer of some sort but can't find where it fell from (first three pictures), It just sort of got stuck near the bolt that attaches the shifter to the bar.

I took out the remains and it still rattles.
A small plastic cover (fourth and fifth picture) seemed to be loose so I tightened it but it still rattles. Everything else looks alright I guess?

Then, I recorded the rattle sound and it somehow started going away as I recorded. Then I went for a ride and the rattle came back.

Any ideas? Or should I just go ahead and take apart the damn thing. Found some videos about 105 shifters rattling but they were hydraulic 7020s and these are mechanical.