DanLo

Similarly I just notice another similar error with Latex formulas with apostrophes. Here's an example... should be way simpler to explain :  I don't know why but Language Tool...

In fact PDF is a standard initially created by Abode, so..... But we could easily use an icon like this one I guess :  Source: wikipedia PDF large icon.

I installed it via the gnome extension web page.

Had the same problem before on 18.04, got corrected since then (clean install of Ubuntu 20.04 + clean install of the extension).