wrong text font

[Stefano Carbonelli]

Hello,
first of all thank you for working on lilypond.

I am using lubuntu 20

I have just installed lilypond and when I run it, texts (chords, instruments 
name...) are shown with a wrong font (containing big symbols, not usual 
letters).
The same .ly files worked fine in my previous computer with lubuntu 16 and 
lilypond \version "2.18.2" 

The same happens in frescobaldi with new documents, I attach a screenshot of it:
www.stefanocarbonelli.it/screenshot-70a3101e.jpg

Since I did not find the problem discussed online, May I ask here if the 
solution is known?

Thanks

Stefano Carbonelli