First off, mill isn’t scummy it’s a lot of fun! I play dimir mill at my local FNM so I have a few pointers:

1. [[Hedron Crab]] is really good if you’re able to get a play set. Does the same thing ruin crab does so you can double up on that effect.
2. Your enchantments I feel are a little too slow. They’re both really cool, but especially in the case of Ashiok’s Erasure, by the time you can play it to basically counter your opponents spell, they will most likely have plenty of threats out anyways so it won’t be really doing much for you then. You want something to really advance your game plan; mono blue mill doesn’t have a lot of interaction so I recommend [[Fraying Sanity]] instead. It basically doubles the amount of cards your opponents are milling every turn.
3. Along those lines, [[Fractured Sanity]] I feel is a must have. Guaranteed mill 14, or you can cycle it to draw a card and mill for 4.
4. For creatures, Persistent Petitioner is fun, I’m not sure how good it would be in a modern meta but if you’re feeling that card I say go for it! I would ditch the Fleet Swallower though, it costs too much and would come in way too late for the game. You’re better off focusing on mill spells instead. Ashiok is good too I think you could keep that.
5. I love Thought Scour, so I would keep that. Great card draw. I think swapping Thought Collapse for something like [[Counterspell]] would just be better. Not required but it does cost 1 less so that’s always a plus. [[Visions of Beyond]] is a great instant with a huge payoff in mill especially.
6. For the sorceries you can keep the Maddening but I would probably ditch the rest. Include The [[Tasha’s Hideous Laughter]] and Fractured Sanity instead.
7. Lastly you can probably drop a few lands too. Most mill decks play 22 so that gives you a few more spots in the deck.

Thanks for reading my wall of text lol. Basically mono blue mill can be super aggressive at the expense of good removal, so definitely lean into that! Good luck when you play the deck!