With the mod enabled all new infinite recipe productivity terchnologies cost only two (+1 for level) science packs, even tho in normal game they cost 1000 and more

I'll look into it, that's definitely wrong lol

After the update it works now, only starting infinity (level 1 for the infinity technology) costs are just 1, but after that it works.

I think the problem is with techs with a cost formula containing 2^(L-F), L is the level to research, F is the first infinite level.
The first infinite level will then cost: BASE * 2^(F-F) = BASE * 2^0 = BASE * 1
But if you replace ^ with * using this mod it becomes: BASE * 2*(F-F) = BASE * 0