I think the many patrols spawning is intended, but the spawn location was bugged. My group is playing on Suicide, and with the Nuclear Radar upgrade it’s easier to see patrols on the map responding to your activity. Kill some bugs/bots at an objective and you’re guaranteed to get one patrol responding to your activity. Drop an orbital or a strike at an objective and you’re sure to get multiple patrols. In rare instances I’ve seen a patrol spawn right on top of us, like literally blink into existence, but the patrol itself wasn’t the issue.

Using stratagems constantly, getting 30+ kills each one you throw, and still the enemies never stop coming.

That’s why the enemy keeps coming. My theory is that the game director responds to your activity. The bigger yours actions, the bigger the response (orbital > eagle > support > primary > secondary). To keep this from being an infinite loop, I would guess the director has a reinforcement budget. The game “going back to normal” was the budget running out. It would make sense if the budget scaled with the size of the squad, so a player dropping could explain why the reinforcements ran out at that time, or it could just be coincidence.

Manipulating this system is how my group clears the “impossible” civilian rescue mission vs. bots on Suicide. If everyone stacks on the extraction area then it gets overrun with dropships within minutes. But if three people run around outside the civilian extraction area, making as much noise as possible and kiting the reinforcements around, then the drops are pulled outward and the extraction area stays mostly clear. One person is the Button Man and focuses on summoning civilians while killing any stray bots in the extraction area with as little noise as possible. Eventually there will be some drops in the centre, usually when the Button Man runs out of secondary ammo and the distraction crew runs low on orbitals/eagles, but the objective is usually 80% done by then and we can converge on the middle the get the last few out and extract.