Doesn't happen here:
15:05:46: Geany INFO : Geany 1.37 (git >= 915cf6e8), en_AU.UTF-8 15:05:46: Geany INFO : GTK 3.24.20, GLib 2.64.3 15:05:46: Geany INFO : OS: Linux Mint 20 (ulyana)
Try a different font.
The font face is defined by the colour scheme, perhaps try [one](https://github.com/geany/geany-themes) that does not use bold (or make your own).