And who will pay the miners if all txn fee subsidy is off chain on a third party network?

Bitcoiners so far up their ass they can't even read the abstract of the Bitcoin whitepaper, or they do and either don't understand it or completely ignore it because some influencer told them that it's the way forward.

There's a reason why Satoshi hated developers and wanted a protocol that wouldn't be fucked by them, yet here we are.