OKW Volksgrenadiers are supposed to get passive healing at Vet 5 not at Vet 4. They are supposed to get a sight bonus at Vet 4.
Please refer to the screenshot (you can see the passive healing icon on the unit card.)
Raise a Volksgrenadier squad to Vet 4 and take some damage. Put it out of combat for the passive healing to kick in.
Any mode without any mods
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