I stumbled upon another issue that appears related. On the English Wikipedia page for Croatia, the pronunciation of the Croatian name Hrvatska in IPA symbols is mangled beyond recognition. The text in question is, in ASCII (minus the & and with spaces added for clarity),
[ x #x0159; #x0329; #x028B; a #x02D0; tska #x02D0; ]
Character U+0159 displays correctly, but the other three character entities do not. The Apple Dictionary app displays them correctly, AS DOES CHROME.
I am currently using Brave 1.36.119 (Chromium 99.0.4844.83) and Chrome 99.0.4844.83 on MacOS 12.3.0 (x86), which suggests that this problem is at least partly in Brave itself rather than in the Chrome engine.