HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

Regarding the artifacts in the second picture, there's a suggestion that some application, like a player or one using transparency functions when memory is low for graphics processing, is running in the background, even in minimized mode.

I turned off all applications and checked again. Unfortunately, this discoloration remains, both with and without the mod. I repeat: in versions where there are still four slots, this bug does not occur.

Something is unclear about the slot.

It's strange that the fifth equipment slot for the hero in the merchant's window doesn't display at all. I think this is related to the fact that the merchant was originally programmed for four hero slots, as it was in the original game. With the introduction of the fifth slot, they apparently forgot to rewrite the merchant.