Hey I think this is a bug. The original factory I have keeps getting destroyed from the outside. I get an alert for damage. I see health going down and then the inputs stop and the combinator goes to being a normal combinator.

Are biters eating the base on the outside because of pollution?

Taking damage: https://pasteboard.co/g0jNyUPrmuNM.png
Damaged: https://pasteboard.co/GTWeb61PF0rJ.png
no inputs: https://pasteboard.co/y82NQ9t8chcA.png

Fixed it for now. I went to the navis surface and set the building to indestructable.

not sure about how many biters will spawn there killing my frames though :P

Yeah this is caused by the biters attacking the building. The factorissimo playthrough preset removes biters and pollution. I'll see if i can make it never spawn biters.