I haven't seen much on this topic so I wanted to see if anyone could shed some light on it.
When I first started playing the game I obviously assumed the player spawns were randomized between all the possible spawn locations, depending on if you were playing PMC or scav. However, after playing for many hours I now find that very difficult to accept, considering there are a rather large number of potential spawn locations, and yet it's very common for my squad and I to spawn in the same location 3-4 times in a row. Even as a scav running the same map repeatedly, I find myself spawning in the same location over and over again. Statistically this would be extremely unlikely if things were truly randomized. And yet it appears that others have a similar experience as well.
So is it based on level? Squad size? Load speed? Something else? If you have some ideas then let me know!