Some websites attempt to defeat Ad-Block, Ad-Guard, and U-Block-Origin [installations] activity of your Internet browser.
Opposing such website attempts (to defeat your defenses), are some ad-block/hiding filter rules (working for your defense) that are active as a result of such installations.
Those [installation] filter rules probably affect the success of a Brave Browser user’s own, custom filter rules.
I tried some custom filter rules, including what you tried - but the Facebook and Twitter social media buttons you point to, remained.
PS re anti-AdBlockers
Advertisers and Websites
My view, is that more websites are on the offense against the privacy of Internet browser users. Such websites have playbooks, in effect, of dynamic responses to a browser’s defense.
And as time passes, there are more tools (including anti-ad-blockers) for the websites, and thus, more complex playbooks. Resulting in websites becoming hypersensitive about
Re the first part of that, seems to me, that websites picked up on the tools used by advertisers - behaving as hackers, searching for holes in your armor and walls.
Each hole and piece of info that reveals something about your device and software, is a focal point that becomes part of the overall fingerprint . . . for only a brief moment . . . until the next risk assessment that is sometimes only 150 ms away from the previous.
The website playbooks changes, and that is frustrating for the producers of ad-blocking filters. Such producers struggle with defending against the anti-ad-blocking tools of the website.
Example from one of the recent Fanboy AdBlock lists (May 5, 2022). The example shows lines (by the producer) intended to frustrate the efforts by websites that are trying to defeat ad-blocking:
You may download and study the PDF file. Peter Snyder and others of Brave Software, are authors of, contributors to, the article:
‘Blocked or Broken? Automatically Detecting When Privacy Interventions Break Websites’