Blocking cut+paste is a clumsy, ill-conceived thing to do on any input control. Don't do it.
This is a solution to a non-existent problem and sadly just represents undesirable cancer-like behaviours on the web. Browsers/password managers offer to save credentials these days. Even if they are entered erroneously, they're saved. And, there's always "forgot password" if you lock yourself out inadvertently.
All this type of thing does is frustrate competent users.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.