If this was refereed properly, #1 there'd be a penalty,#2 both Swiss defenders would pick up a Yellow Card, and be sent off if they already had one. Both Swiss players should theoretically be sent off, as it was very unsportsmanlike and they teamed up to obstruct the Serbian.
The game would be very different game if this was refereed properly.
Where was the VAR team? Out on a Vodka break? This is a comprehensive failure of 11 people.
There's absolutely no way that this incident should/could have got past this, which lends credibility to Serbia's claim that the ref was biased, especially when the officials on the field should have noticed this without VAR.