Use it together to Old Layout for Facebook by Matthew Krause.
They will revert almost everything, except home page, settings page, and MarketPlace (that using those extensions you will see it as it on mobile mode, a real mess if you´re a seller, coz you won´t only see the MarketPlace items you´re selling but the group´s ones -if any- all together; thats one of the reasons I hate the Facebook app, it lacks of functionalities, and the MarketPlace is awful).
I already sent an email to Matthew, so a fix will come out in any moment.
Furthermore I have to inform you that yesterday I had to disable Revert Site addon to edit a note on my group coz Facebook detect that addon and its making a misunderstanding: inserting a link on the note is interpreted as if I´m hot linking to F.B. Purity (the other addon behind Revert Site) website but not in a clear form, even if I was making a link to a completely different website.
So I neeeded to disable Revert SIte for a while, edit / create the note with links on my group, save it, and then reable that addon.
IMHO FB its making a war to those addons coz they don´t want the new UX be reverted (you should know how Zuckerberg acts), so we FB users should go on with a Change.org / Avaaz petition asking FB to revert the UX to the previuous one and to give us back the notes on our profiles.
Let me know your opininion.
Regards.

@st333v Hi, I´m using Opera Developer 73.0.3847.0 x64 and can´t even fix your extension on the main Opera´s bar.
I´ve tried to uninstalll and reinstall it several times but it just appears for a second.
This way I can´t have access to the extension features.
With the Old Layout for Facebook (broken again both in Opera and Chrome, fuck FB), it doesn´t happen.
What does it depends?
Is there a workaround before to trying the FB old design workaround?
Yours sincerely.