and reported to Maple Support

It's really good. But i'm not suare the version on mine Laptop will update, because the term of updaiting ended in 2021.

What type of Monitor do you use?

HP laptop 15s-eq2037ua.

Can you try other displays?

Yes, I tried several PC with big Monitors and Notebook. As I've noticed this effect not depends on displays. Font in plots gets smaller in pdf.

Do you see the reduction in fond size also in the newly introduced print layout mode?

Unfortunately, I don't know what is "print layout mode". In Maple 2021 I can't find this option.