This addon works with the same source code in both browsers.
And easy to see that their code (Firefox, Chrome and Source code) is the same,
such as using an "Extension source viewer".

Extension source viewer:
https://addons.vaultpit.io/en-US/firefox/addon/crxviewer/

Source code:
https://github.com/saihon/remove-element

Chrome webstore page: https://chrome.google.com/webstore/detail/removeelement/jjhnenbbbbgojdbealmpdkmbkbnmeimf

Thanks!