ℕ copied as N
Let's consider the document qq.pdf. It contains
ℕ (U+2115) as reported by
pdftotext. However, copying the symbol using Ctrl+Ins and pasting it into
gedit produces a plain N. Apparently, this does not happen with Foxit (cf. https://tex.stackexchange.com/questions/475585/ℕ-goes-as-n-into-the-text-layer), which copies the Unicode char ℕ. This bug (or feature, depending on your viewpoint) of
evince is definitely worth being improved.