How units gets "weird" experience?

I think i not the one who saw how sometimes fresh unit in lategame got fullvet. Like cons get 3 stars from one AT nade of couple shots to german soldiers, or volks instaget 5 stars. How it works? I very often saw this for infantry units, sometimes for team weapons, but never for tanks. But should say that for tanks i sometimes saw how t-34 got 1 star in engagement (where t-34 will be lost anyway) and then right before death got 2-nd star (it looks like the 2-nd star was got for gotten damage not for dealed damage).
There is some kind of lategame experience buff for all units or what?

Shooting vetted squads gives bonus vet.
20% per star.

Shooting vetted squads gives bonus vet.
20% per star.

DAFUQ?

2500 hours in game and this is a new one for me
I knew about differtent vet values for different units, but not that they change with vet

Shooting vetted squads gives bonus vet.
20% per star.

It means that for OKW 5 stars i will get 100% bonus while for OST i only got 60%? But it don't explained how couple shots or 1 AT ande or faust give you full ACE vet. Ace veterancy it is big chunk of experience. The same squad couldn't get ace vet on first 10 minutes of game where engagements the most intensive, while in late 1 shot to enemy and you are hero of war.

It means that for OKW 5 stars i will get 100% bonus while for OST i only got 60%? But it don't explained how couple shots or 1 AT ande or faust give you full ACE vet. Ace veterancy it is big chunk of experience. The same squad couldn't get ace vet on first 10 minutes of game where engagements the most intensive, while in late 1 shot to enemy and you are hero of war.

Shooting more expensive units gives more vet too.

Shooting more expensive units gives more vet too.

For example, why you're basically guaranteed at least a third of an vet level from having an infantry unit's snare successfully damage a tank.

DAFUQ?

2500 hours in game and this is a new one for me
I knew about differtent vet values for different units, but not that they change with vet

Yep, you can see this in basically all replays, just enable the XP info bars that pop up when a unit kill an enemy model.
See how much XP you get at the beginning of the game when your units kill an enemy model, and then later on when they kill a model of the same, vetted squad. Don't know about the exact increase, but Katitofs 20% seem about right.

It means that for OKW 5 stars i will get 100% bonus while for OST i only got 60%? But it don't explained how couple shots or 1 AT ande or faust give you full ACE vet. Ace veterancy it is big chunk of experience. The same squad couldn't get ace vet on first 10 minutes of game where engagements the most intensive, while in late 1 shot to enemy and you are hero of war.

This is how it works.

-Veterancy is given by both doing damage and receiving damage. IIRC it's around 3 times more effective to do dmg than to receive it. Kills don't matter as in vCoH.
-Some units can gain passive xp through been near the action. The value is small though (look on changelog for specific values).

-Cheaper squads tend to have lower unit value as well as well as minor xp requirements to vet.
-Vehicles tend to have a really big value. This is why vehicles which are AI mostly, might have a harder time vetting than vehicles on AT duty.
-While more expensive vehicles/units have a higher value, they don't translate 1:1 with mp and fuel cost. Specially call ins (the call in cost is not the same as the mp/fuel cost for the unit per se) and support weapons (same logic as call ins, the crew is cheaper than the overall total cost).

-When units vet, their value increases. It's not additive, it's multiplicative. So it's 1.2/1.44/1.728/2.0736/2.48832

From the changelog:

OKW Veterancy
With the changes to OKW veterancy, the high values OKW units awarded when damaged are no longer necessary.
Veterancy 5 for select units no longer increases the unit’s current value, reducing the amount of experience they give to other enemy units that hit them.

-Requirement to vet are double with each vet level.
-For OKW, vet 4/5 are either 25% or 33%.


Tests:
Vet 3 KT

Vet 0 cons: get 33%/90% xp of a bar, based on penetration with a normal AT nade.
Vet 0 cons with PTRS package: a full 6 man volley from behind, will make them vet 2 and 25% xp.
Vet 0 Penal: a satchel gives you vet1 and a half.

also, taking damage gives you xp but don't make you go over the next veterancy level, you need to do some damage to get the next star