Re: Libre Relay, people might be interested in my bitcoindev mailing list write-up on how it has been used by LN nodes to get pinned transactions unstuck: https://groups.google.com/g/bitcoindev/c/n2GNmnz0btw The Lightning protocol does have a few remaining transaction pinning vulnerabilities, so anyone running a LN node should consider running Libre Relay.

F2Pool has, so far, been the main pool fixing transaction pinning. I believe this is due to them having a shorter than usual transaction expiration time on their nodes; I don't think they're running replace-by-fee-rate itself.

A coinjoin with a fee that is too low is basically a case of accidental transaction pinning.