Those are hex head bolts or whatever i dont fuckin know what you call emm, not sure what those are off of.
Im almost 100% sure 240’s at least as ive worked on a few use grade 10 or 12 cant remember solid bolts…
My car does as well…
Pete im not saying its not worth it to get new bolts
6 new flywheel bolts will cost him 4-5 bucks at fastenal
Ando those look like they were cross threaded and over torqued