Currently playing "FTB Skies" (Minecraft 1.19.3) where i have updated to the most recent version (1.0.7).
The price my villagers sells for in my auto traders are increasing, even after i have sent them through the converter multiple times.

Server setting wise the "universal_reputation" is set to true.
Is it because of villagers increasing/descreasing price depending on demand in the new minecraft version?
Haven't played in some time, so this felt/fells weird, almost like a bug.

If so could an option for the auto trader be added allowing the player to set a max price they want to buy/sell for?

This completely depends on the mods that are installed alongside. The mod just simulates trading with a villager.
Adding a cap for the item amount might be a good idea.