Firefox's "Don't allow websites to use custom fonts" option makes the Web feel much more cohesive and polished.
https://addons.mozilla.org/en-US/firefox/addon/enforce-brows...
I personally block fonts via uBlock Origin, which lets me allow them for the subset of websites I visit regularly enough that I'm okay with allowing fontawesome-style fonts.
It doesn't help with icon fonts based on ligatures instead of PUA characters (Google's Material Design framework seems to do this) but we can't have everything.
https://i.postimg.cc/Gm8L8MPy/sw-appy-20210813-193924.png
In case that website blocks hotlinking: https://postimg.cc/gallery/RVSBXh7
The first image shows https://twitter.com/newsycombinator with devtools on the right showing that the computed `font-family` for that one span has "TwitterChirp", and the uBO logger at the bottom showing that chirp-*.woff fonts were blocked by my uBO rules.
The second image is the Fonts tab of the dev tools showing that the font that the browser is using is Roboto, which I have available locally.
As for how I do it, see https://news.ycombinator.com/item?id=26284124 . If you don't want to go that far, you can still create a rule just for twitter.com that blocks just the chirp*.woff URLs.
*:not([class*='icon' i]):not(i):not([style*='icon' i]):not([aria-hidden='true']):not([aria-label]):not([class*='fa-']) {
font-family: "Operator Pro" !important;
}