For starters, reopen Luck’s PR from 2023. And then look deeper into Datum and what the guys at Ocean are doing. So much misinformation still doing rounds about that and adopting Datum by other pools is the way to finally start fixing mining centralisation.

Cap witness data to 400kb and try a reasonable small limit on OP_RETURN of like 4kb or something and monitor to see if it's an effective release valve. Combines fixing the problem with a cautious systems approach to a solution.