So in both cases, it's just poor web design. This is disappointing.
I could maybe forgive the use icon fonts (Google websites end up breaking the most, android's documentation website for example) but it's unforgivable to write `pre code { font-family: my-random-webfont }`.
Something I can add since I started blocking remote fonts completely in uBlock Origin a couple of days ago: I’ve been noticing lots of broken icon fonts now where I hadn’t before; my working hypothesis is that under the flag we’ve been talking about, Firefox excepts Private Use Area code points and happily loads web fonts for those specific cases. Thus, the cases we’ve been observing of broken icon fonts are where the fonts didn’t use the PUA, whether they tried to choose decent fallbacks (like DuckDuckGo), or used the ligation technique (Material Icons), or just did something weird for no obvious reason.
I could maybe forgive the use icon fonts (Google websites end up breaking the most, android's documentation website for example) but it's unforgivable to write `pre code { font-family: my-random-webfont }`.