Do password managers fill out hidden form fields?

Question

Browsers

Greetings
Surely you know all kinds of programs and extensions for automatically filling out form fields such as LastPass, RoboForm and others. I would like to know for sure whether such password manager programs fill in hidden form fields on sites. It is not possible to find and test the operation of these programs on all possible platforms with different browser variations, but you need to know!
Why do I need it? - Fucking spam brings down through the forms on the site. I wanted to try to add a hidden field and check it for fullness. If filled, then immediately send to spam or block the sender. But there are concerns - if a normal person has this kind of software installed, then I would not want to mark him as a spammer bot.
Are there any considerations or confirmed data on this issue?