It's likely that system only has the base Latin-1 font set for some weird reason? Or a misconfigured fontserver (or equivalent in Windows). My understanding is that the text "sail the high seas" uses glyphs in both the Latin D group and the phonetic extensions groups (feel free to correct me!), so pretty much any Unicode-aware font since 2010, FOSS or otherwise, would render this correctly.
I personally recommend the Liberation font set, although it's free software so you can't really pirate it.
(I honestly wouldn't know how to answer the question. I guess in order to pirate it, you'd have to fetch a copy from someone who broke the license terms and is thus not authorized to distribute it, but that kinda turns into a Catch-22)
Yeah I just checked Atkinson Hyperlegible and, at least the version I can access (the one on Github) lacks entire Latin and compatible character ranges, as well as having a substantially limited math symbols set (only two greek letters show, for example).
The weird thing is, if I understand how fonts correctly, that shouldn't have been an issue. The font doesn't register those missing characters, so your browser should have known to fallback to a default typeface for the missing characters. It'd be weird if you have none of the many compatible fonts (not even, say, Times New Roman).
![[Solved] What font am I missing?](https://sh.itjust.works/pictrs/image/227cd3d7-bb73-4f3e-8b4e-b9539548b14e.png){kind=link}
