If the same argument happens every holiday, someone has to try a different line. It might as well be you.

Repeating conflicts are systems, and a system runs the same way until one part behaves differently. Everyone involved is waiting for the other person to change first, which guarantees another identical round. Whoever breaks it is not conceding the argument; they are declining to play their usual part.

Decide before the next gathering what you will do instead of your normal move. Ask a question where you would usually defend, or step out for five minutes, or let a remark pass. It will feel unnatural, and it is the only lever you actually control.