Right click on any button of the toolbar and select Customize Toolbar... from the context menu. The customization page opens. In the bottom left-hand corner, tick the checkbox Title bar.
This restores the behaviour of Firefox before version 89. If the checkbox is not ticked, Firefox tells your window manager to not add a title bar.
Half solution but better than nothing:
You can turn off the default spell checking in Firefox ( layout.spellcheckDefault set to 0 ) and then use the https://addons.mozilla.org/pl/firefox/addon/languagetool/ extension. (recommended by Firefox)
Now you can get permanent domain exclusion in this extension:
or that way:
I know link only comment is bad but the primary answer is available here:
Visit a website that offers an OpenSearch search engine (Brave Search supports it).
Right Click on the search bar
Select "Add Brave Search"
Is there a way to prevent a site from doing this blocking via settings, or additional plugins?
Per an answer to this Stack Overflow question, it is possible to disable Content Security Policy browser-wide in Firefox by setting about:config → security.csp.enable to false:
This setting was confirmed to still be available as of Firefox 89.0.1 (June 2021).
If the about:config setting of layout.css.devPixelsPerPx persists,
but has no effect after restart, this is most likely a bug in Firefox.
Before signalling the bug, try disabling all extensions in about:addons,
to see if this is caused by bad extension. See also
How to Uninstall or Disable Extensions in Mozilla Firefox.
Otherwise, while waiting for the ...
What about Vim Vixen?
Vim Vixen is a Firefox add-on which allows you to easily navigate the
web by keyboard. Since version 57, Firefox has migrated to the
WebExtensions API and has dropped support for legacy add-ons. Vim
Vixen is a new choice for Vim users since it uses the WebExtensions