Yes, and looks like I've already found the solution - it's about some missing headers. I'm testing it right now and will drop it here and on StackOverflow too if it works.

In reply to Re^4: How to set up a correct custom User-Agent when using Perl's Selenium::Remote::Driver and Firefox by Jaharmy
in thread How to set up a correct custom User-Agent when using Perl's Selenium::Remote::Driver and Firefox by Jaharmy

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