Please, for the love of all things holy, stop causing structures to go offline while upgrading.
First, if something is supposed to go offline it should only happen while the upgrade is happening, not while it’s in queue.
Second, can infrastructure buildings (farms, power, climate, hydro, etc.) not go offline. I’m fine with mines, labs, shipyards, scanners, etc. being down. The infrastructure stuff means that either pop starts dying, or everything goes offline.
Hell, make something in the tech tree for each structure type called redundancy or something.
Right now I’m working on upgrading a lot of structures to T2 and this is turning into a nightmare. Having to go into each planet and build an extra structure (or multiple) then queue up a couple upgrades, and repeat that (in some cases 20-30 iterations). If we just go with power, farms, climate, hydro, and army base that could be anywhere from 30-60 upgrades (twice over if going for T3). Take that times 36 colonies and… Holy Upgrades Batman.
If they only went offline during upgrade then I build one extra and I can queue up 30 farm upgrades at once. If they didn’t go offline at all then I wouldn’t even need to build the extra.