Confirming that with libfreetype6 older version 2.9-lp151.3.3 I get exactly the same error, while with the current 2.10.1-lp151.4.3.1 everything is OK.
Yes. I’ve locked the freetype version due to the bug.
Maybe it is better to wait for a fix arrive in the repos than setting variables I’ll surely forget three minutes after doing it, and perhaps later have conflicts or degraded visual performance due to these changes. I’ll give it some time.
Thank you both malcolm and OrsoBruno. I’m always amazed at how much you know and how much you help us.