Disclaimer: I have no idea how to build a Muldrotha deck outside the obvious "recur creatures with powerful ETB effects".
Just looking at the EDHRec Muldrotha page, you are missing a lot of fantastic cards, like:
MulldrifterShriekmawSakura-Tribe ElderFleshbag MarauderEternal WitnessWorld ShaperUnderrealm LichYou seem to only have
Mulldrifter and
Eternal Witness in your list of "sideboard" cards, but they work really well with Muldrotha. I'd like to add those to Morganator 2.0's list of cards that need to be in your deck.
Maybe you aren't building your deck like a creature deck that sacrifices creatures and recurs them with Muldrotha's ability. If not, then some of the listed cards are a little worse.
Some cards I noticed that don't work too well with this deck:
Silent Arbiter (pretty focused hate, but if you're really worried about those token decks, leave it in)
Ulvenwald Hydra (Muldrotha's ability makes it so you can hit your land drops easier, but you aren't running a land-focused deck so you lose some value)
Vizier of Tumbling Sands (not a lot of good targets for Vizier's ability. The cycling makes it a little more enticing, but I like
Mulldrifter better as a blue (evoked) 3-drop)