Linux Mint 21.1: symbols with pixels

Hello, I recently installed Mint 21.1 on Samsung R500 with Radeon Express 1250, and I see, that some characters on the screen are very "pixeld" - s. attached photos.

This is not my first installation, I never saw it earlier. Can anyone give a hint how I can resolve the issue?

I tried already to search for a driver using Mint's tools - it says "No driver is needed".

Regards,
Andrey
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