Speaking of reinforcements with how good Gravenbech was in the first match, the loss of Zubimendi may not be felt so much, wonder why Klopp never tried him as a holding midfielder.
Because he ain't a holding midfielder. He can have a good game against a weak team where the control is Liverpool's, but in a more even game I doubt he'll be considered at all - Endo will probably get the nod.
If however Gravenberch does play the 6, it will be in a double pivot with a player that isn't a 6 as well - example McAllister.
It can work temporarily - but long-term it won't bring us trophies.