This extensions apparently is not maintained: it hasn't been updated in two years; also, it has some no longer used code, e.g. /data/services.js is no longer used because the data was moved to /data/services.json. Furthermore, Disconnect is rather limited in features compared to uBlock Origin, AdGuard, Adblock/Ablock Plus, etc. Specifically, it uses domain-based filters, so is unable to block site's own tracking. You might as well install a hosts file and/or block third-party cookies and get pretty much the same result as with Disconnect at a fraction of resource use.

I noticed the 'show counter' box rechecks itself, usually after a reboot or two, so that the number of tracker requests eventually reappear on the menu bar icon. I've unchecked the counter box any number of times.
Edit: Also noticed the drop down menu sometimes doesn't render as it should. Have tried removing the addon, quitting FF and reinstalling but without success.

Estou usando há anos. Protege sua navegação contra rastreadores e não deixa que Facebook, Google e vários outros saibam o que você faz. Também deixa a navegação mais rápida e só é necessário desativar quando você realmente precisa vincular o site ou quando quer ser rastreado. Parabéns aos devs!

Useful information. It really puts me in control. Thank you, devs!