If my country gets its population reduced by more than 50% as a commie (say from 100+k pop to 40k pop), but all things being relatively equal (no. of indy complexes remains the same except maybe with a slight reduction-- lets say from 16,000 indy complexes to 15,400 and tech levels remain the same) can it cause my indy production to drop drastically? -- by drastically, I mean by more than 60% fall despite the fact that my absolute number of indy complexes have only dropped by 3%.

I was producing 60k+ turrets but after suffering a series of guerilla strikes, I am now producing only 20k turrets, despite the fact that my buildings remain mostly intact and my indy tech level remains unchanged. Is this normal?

yes

yes it affects and yes it's normal and yes it sucks.

it returns normal when your pop has reached near current max.

The guerrilla strikes killed your factory workers my friend

Is there a formula for this? I don't see it here https://wiki.earthempires.com/index.php/Game_Formulas

no

Yes, there is a formula.

The formula is not public. It is known tho.

It is public. :P

Unless forums is not public.

You simply fall below 80% max population and you begin to lose production.

Hint: Marshal posts a message after the person who posts the formula on a thread.

Hmmm