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

HoMM3 HD 3.0 RC4

Thank you very much for this! :)

Because of this, I might be able to make it possible to play with autobattle in online mode, but only HD vs HD, so that everything is fair.

But we don't need that.
In most cases, a better result is achieved in manual mode than with autobattle. But autobattle is a convenient feature that allows both players to save time. And with only high-level creatures, it achieves approximately the same result as in normal mode. But sometimes, stupid losses due to it limited its use. The ability to replay in manual mode solves the problem.
In short, leave it as it is.