I'm also curious about withdrawal fees- does it depend on the size of the mempool as well? These past few days it's been quite high (50+ sat/byte) but it's come back down to 15 sat atm so I was wondering if we can choose an even lower tx fee.

Actually from what csmiami said above, withdrawal txs are already paying ~15 sats/byte but us users are still paying higher so I guess that's what he's asking about.