matejfore, you may disagree, but this is how the gamemechanics work. It's not an error, it's how the devs programmed it.

In this topic, there is another layout with which you can have 1, 2 or 3 output products on a farm (and have 100% utillization in all units)

I must disagree. As you see from the picture the top processing unit has a surplus of supply when the left and the right unit are suffering from supply. In real life a surplus would be transfered to the units that don't have enough supply.
It seems that the top unit is somehow preferred.
You are probability asking why, did I implemented such layout to the firm. The reason is, because you can easily switch to producing eggs if the demand on the market changes. It can be done with all livestock farms. This error, doesn't seem to happen on a frozen beef product ?

What i see is this:

3 raising units trying to supply 4 processing units. As i said in my post above, this is not going to work 1 raising unit can supply 1 processing unit.
There is 1 units with lvl 7 while the other(s) are 9. This is possible though. (The following info i cant see in the picture so consider it an assumption) Training of units in caplab is done according to utillization. If 1 unit runs not on 100% for some time (mostly this happens at the start of a game or placing of new firm, because demand has to build up) while other units do run on 100% utillization, that unit doesnt advance in level as quick as the 100% units.

Let me know if im right or wrong or have missed something, as long as im playing cap2 and caplab, i too learn every day i play the game still

My suggestion is as follows:

Your sales unit at lvl 9 sell the frozen chicken much and much faster then your processing units can supply. So switch the sales unit at the rightbelow point to a raising unit.
That way you have 4 raising units with 4 processing units. Switch connections so that 1 raising unit connects to 1 processing unit, otherwise they are gonna supply eachother which can lead to a processing unit not receiving a good supply while the other is oversupplied. Ofcourse this 4th raising unit need some time to train to lvl 9, but since demand at the farm is higher then supply that raising unit will run on 100% so training is at max speed

Please look at the picture, there is wrong something with distribution of livestock.

This was the case in Capitalism 2 yes. If i remember correctly it was: 1 raising unit = 1.5 processing unit.
But in Capitalism Lab, 1 livestock raising unit can supply only 1 processing unit.
If demand is very low resulting in your stock in sales and/or inventory units are full, the raising unit can supply another processing unit but thats because the stock of the first raising unit is (probably) full.

Noticed the same thing

Whenever i create a farm and set it up to have 4 processing units serviced by 2 livestock raising units, one of the raising units will only service one processing unit even though its connected to 2. the other raising units works fine and supplies both. but the other one when connected to both processing units will only send products to one processing and the utilization on the other one goes to 0. this makes the other processing unit totally useless. Is this a bug or what?