So for example, round 2 you have 2 food mules out. Those mules should be worth the price you paid eg. 100$ + 25$ for the outfit(so +250 to assets). How is every mule worth 35$?

mballs
That is my point. The game is valuing them at $35 each in your total score at the end of each round but it does not seem like that is what the game would intend. Looks like it would either fluctuate with the current price of mules or at least state at the $100 round 1 value. From where would $35 comes - but again that is the value after every round of each of your mules.
I tested it on many rounds with 3 AIs in a training game. Every single round all four players assets portions of their scores are valued at resources each owns times that resources current price, all mule equipment at its normal price (e.g. food equipment $25, energy $50 etc.) and each mule owned times $35. Every single time, I calculated it for all four players, after four rounds, that was the value.
Run a trial game against 3 AIs and add up the asset element after a round or two or all 12. You will find the same thing - no matter what happens or what point in game, mules = $35 each in your score.
This can affect in-game round ranking, especially in round 1. For example, someone not buying a mule in round 1, will have a $65 boost all else equal (math -> people who paid $100 now have a asset worth only $35 in their scores.) This often causes someone paying 976 for land to be ranked higher than another player that paid 972 and got a mule out. The latter would have to make production that exceeded value greater than 1 unit of energy (that the none mule buying player did not use) plus that $65 (that the non mule buyer gets his relative score boosted, compared to players who bought mules, since he did not spend the $100 for a $35 valued asset.) Making 1 to 2 foods, which often happens, would not cover that, so non mule buyers often get valued higher after round 1 because of that.