I bought an original CD of Lords of the Realm 1, because, unlike the GOG and Steam release, it contains the additional scenario (conquest of the Holy Roman Empire instead of England & Wales).
When I started it on my Neoware CA2 (VIA C3 Ezra 800, 256 MB SDR 100, S3 Prosavage, Windows 98 SE), but unlike the normal version, which works fine, I see this weird mess for the graphics.
Disgruntled, I mounted the same folder in DOSBox on my main PC (Ryzen 9 3900X, 32 GB DDR4-3600, Geforce 2080, Windows 10) - and it looks identical!

What could possibly be the reason for this?

I made a screenshot on my main rig, but it looks exactly the same on real hardware.