Which app is asking for a new App-Specific Password?

I have 2FA set up on my apple ID. On bootup my MacBook Pro asks a few times for my iCloud Password. I enter it a few times (slightly annoying). Then this dialogue pops up (more than once):

Clicking the "create" button takes me to my Apple ID page where I can generate app-specific passwords ... but I don't know which apps need these or how to enter them afterwards, which makes the process quite useless.

Any ideas on how to figure this out?

Thanks,