Some webpages in Japanese (e.g. https://www.jsps.go.jp/index.html) are no longer properly displayed and I cannot seem to find a way to change the text encoding for those sites.
Can you attach a screenshot?
- use a compressed image type like PNG or JPG to save the screenshot
You can check in Font Book for font issues like corrupted and duplicate fonts.
Should have thought of that earlier... Here it is!
This can happen if the font that is requested is corrupted or otherwise can't be accessed, possibly because the font is under control of a third-party font manager and is located in a non standard location. If Firefox isn't able to access the requested font then it falls back to a 'last resort' font that shows all glyphs as a '?' or an 'A'.
You can right-click and select "Inspect" to open the built-in Inspector with this element selected.
You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Fonts tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website.
Thank you for the explanation. I was able to access the information (I think, see screenshot), but I am still at a loss about how to go about fixing it. Or even why the issue arose because this site (and others, from totally unrelated Japanese content) still worked fine a couple of days ago.