I have not tested this. For all I know it signs into your bank account and transfers all your money to someone overseas. OTOH maybe it works.
This "apple extension" i's 100% legit.
It's about 11 lines of code that use CSS (webpage styling) and it puts "display: none" (don't display) to the elements that hold the scores, effectively removing them from being displayed. The "Source code" is what code is in there, that's the only thing - so I can vouch as a programmer that this is totally legit
...As for "Stylus" itself, I checked the website and did some research, here's the privacy policy: UserStyles.world
seems legit, but depends if you want to go ahead and download it, that's a personal decision. Personally I see no issue here, it's an open source repository so we can see all the code and if there's any "foul play", and it looks community-driven for making fun styles on websites.
Hope this is helpful to anyone else that looks into this!
if you are a bit more savvy, you can also use local overrides through the chrome/firefox dev tools. no need for extensions or plugins.
even though I will go this route, i'd much prefer a native solution from apple/MLS.