Thank you, Js, this is the only tab unloading extension that works with my Firefox, because it uses the native command browser.tabs.discard(tab.id) instead of the ported chrome.tabs.discard(tab.id) like all others.
So, to all those who have commented at other tab unloading/suspending/discarding extensions that those don’t work for them: use this one.
And to all the developers who happen to visit here: Mozilla’s online documentation for its Web Extension API specifically states the browser.xxx architecture. User it, don’t be lazy and expect Chrome porting to always work. Not all of us have Chrome Store Foxified.
Spread the word if you know any developers personally. This is important. Thank you.