Why can't I download videos on YouTube Premium using my iPad?

I have just updated iOS18.1.1 on iPad the yesterday before during worked. Then today I cannot download video from YouTube premium. I mean went I click on download. The icon shows me that they are downloading but it’s not appealing on download channel not even once. I try to go at settings but I don’t know what to do and fix it. Please help me.

[Re-Titled by Moderator]