Remove Facebook "Sponsored" and "Suggested for you" elements (causes some errors in the while loop but I don't care, I'm just happy the ads are gone.

remove_fb_ads.js

const hideAds = () => {
	document.querySelectorAll('[role="feed"] [data-pagelet]').forEach(el => {
		let spEl = el.querySelector('span')
        if (spEl && spEl.innerText == 'Suggested for you') {
            el.style.display = 'none'
        }
	})
	var sponsoreds = document.evaluate("//span[contains(., 'Sponsored')]", document, null, XPathResult.ANY_TYPE, null );
	var sponsored = sponsoreds.iterateNext();
	while (sponsored) {
		var r1 = sponsored.closest("div[data-pagelet*='FeedUnit']");
		if (r1) {
			r1.style.display = 'none'
		}
		sponsored = sponsoreds.iterateNext();
	}
}

const enabledSponsorRemoverFromFeed = () => {
	let d = document,
		postFeed = d.querySelector('[role="feed"]'),
		postFeedObserver = new MutationObserver(
			mutations => mutations && hideAds()
		)

	postFeed &&
		postFeedObserver.observe(postFeed, {
			childList: true
		})
}

enabledSponsorRemoverFromFeed()
hideAds()

Use a Firefox plugin like Code Injector and place the code there. It should remove all "Sponsored" and "Suggested for you" poses. Works as of November 16th, 2021.