I found this solution to my browser sucking up resources about a year or so ago.
I run/allow it in private browsing mode, never an issue!!!!!

I have never had an issue until today!

Firefox now opens two windows instead of one as of tonight when I get home 3-5-21.
Disabling extension fixes it, enabling reproduces it.

Using Archlinux - EndeavourOS - 86.0 (64-bit)
KDE Plasma Desktop