Normalization(minmax) gives me worse results than before in KNN, follow up actions?

Question

Hello I'm studying a classification problem with KNN right now.

I have many numeric features that I normalized with MinMaxScaler, I also got some OHE categorical features that not seem to cause the drop, and with this method my accuracy dropped almost 10%.

I used holdout method and cross validation for the results.

What are some follow up actions I could use to try to up my accuracy?

Should I try another normalization technique? Should I try another model ? Anything else?