I've got simple rules to chop the ads from LinkedIn, but if you do an inspect on FB, they've been very sneaky about how the elements are set up, eg it doesn't just say "Sponsored" in a string, it's a weird mash that ends up looking like that when rendered but hard to nail down.
Then again I'm more of a backend dev, so maybe that's why I don't know what to do.
It is designed to be very hard to select automatically. It is also why I don't use Facebook more than 5 minutes a week - it is among the only services where ads annoy me.
> *Important News*: 4th September 2021: Sponsored Posts Issue: It seems Facebook have just changed their code for Sponsored Posts, so some people have started seeing Sponsored Posts in their Newsfeed again, I am working on fixing this, please be patient, thanks! *UPDATE* It seems for some people the sponsored posts are only getting through if your Newsfeed is set to "Top Posts", if you switch to "Most Recent", the Sponsored Posts should in theory disappear. The good news is that FBP has an option to keep you permanently on the "Most Recent" feed when you visit the Newsfeed, so that could possibly solve the issue for now, give it a try and let me know if that solves it for you. In the meantime, I will continue working on a more robust fix.
Under the "Further options" heading there is a setting titled "News Sort: Most Recent". Tick that option, then click the "Save and Close" button.
As mentioned above this is not guaranteed to fix hiding the sponsored posts, but a lot of people are reporting success with it, as Facebook seem to pepper the "Top Posts" version of the Newsfeed with more ads than the "Most Recent" version, and "Top Posts" is Facebook's default setting for the Newsfeed.
facebook.com##div[data-pagelet*="FeedUnit"]:has(div[aria-label="Sponsored"])
facebook.com##div[data-pagelet*="FeedUnit"]:has(span[aria-label="Sponsored"])
facebook.com##div[data-pagelet*="FeedUnit"]:has(a[aria-label="Sponsored"])
facebook.com##div[data-pagelet*="FeedUnit"]:has-text(Suggested for You)