Starting issue with UCBLogo

I use Ubuntu Studio 20.04.2 LTS inside 64 bit machines.

Also, I often use Logo programming language.

Since a while (I'm not sure when this issue started), I get this rare characters each time I start UCBLogo (the native Linux app, installed from Synaptic Packages Manager):

Of course, I can change it, manually, with the UCBLogo panel menu (Fonts).

But... Why is this?

What's wrong, here?

How can I avoid this rare behaviour?