This is a genuine question, and I will be honest: I do not really dislike JS. I even worked on large typescript projects and appreciated it.

What I do not like is the strange mix of technologies you have to cope with in order to work with Python on the web: your project is often a mix of python / html / css / react / js / node.

Many very nice frameworks try to abstract this and present you only the python side; but they rely on this stack internally. Once you want to reach complex use cases (such as a refresh at reasonable rate), you will have to "open the engine" and enter into this mix.

I dislike JS as a developer.... but I also dislike python, so...