Common enough that Mara Pool and CKPool both stop mining subsat transactions because doing so increased their orphan rate too high.
Mara Pool's post on this: https://x.com/PortlandHODL/status/1958520763083825640
CKPool's post on this: https://x.com/ckpooldev/status/1957235824451559746
Mara is still mining transactions below 1 sat/vbyte. They just aren't mining bids as low as 0.1 sat/vbyte, it appears their price floor is 0.5 sat/vbyte.
Wrong. Stale blocks (what the above commenter calls orphan blocks) are very rare, and neither MARA not CKPool have mined any since including sub sat fee rate txs in their blocks. Read the posts you are linking and also see stale blocks here fork.observer
