Same thing with Chrome, 21 processes just on this page here. A lot has to do with extensions that are running in the background. Each extension is one or more processes depending on the extension. when I turn my extensions off, I am down to 12 processes.
It does not bother me much as my PC has plenty of RAM (32GB) and plenty of Processors (12 Core, 16 Threads) so I do not notice any slow downs...