“Bitcoin Core #29496 bumps TX_MAX_STANDARD_VERSION to 3, which makes Topologically Restricted Until Confirmation (TRUC) transactions standard. If a transaction’s version is 3, it will be treated as a TRUC transaction as defined in the BIP431 specification.”

Disappointing to see this merged. It's a crummy proposal that was merged over the objections of others.

It doesn't do a good job of solving transaction pinning, we're still finding unexpected problems with it, and replace by fee rate is far simpler.