Disabling "Ok Google" detection on Google Pixel 3a

I wanted to start using Pixel 3a (my old Nexus 5X is outdated) but I wasn't able to disable "Ok Google". I disabled all that was possible and recommended by a few how-tos but not successful. Did I miss something when I bought this new phone? Where can I disable this? This question is possibly strictly connected to googles pixel 3(a) (dont remove that from the question) Disabled and yet, phone is allways listening and after saying "ok google" it opens a dialog.