Is there a mechanic that allows for scrap or recyclers to turn into their compressed versions? I am seeing compressed copper plates, ore, etc. from my scrap recycling line that I was not expecting. I don't have any compression happening anywhere on the planet or in space.

Not that i know of, i haven't even seen what scrap recycling recipe looks like, nevermind change it :D But that does sound strange, like it lumps in all intermediates. But there must be some filtering to prevent that.

Edit: I can't confirm though, i tried recycling in editor mode after cheating all techs. After it had made 200+ holmium ore there was still no compressed items. The mod is not even part of the scrap recycling recipe.

I wonder then if you may have a different mod that adds that to the recipe?

I also researched possibility of using recipe.auto_recycle property which isn't documented in API, but i would consider if it's needed.

On second thought you might mean something other than scrap is recycling into compressed items? Can you get to the bottom of what is doing it?
... Oh i see now, scrapping iron plates for example.

Should be fixed now.

Came to realize in my playthrough that scrap had no compressed item at all. So new version is out with it. The math on probabilities was harder than i thought and still not perfect with some compress ratios, here of a working example if you set 18 items to compress into 1:
https://i.imgur.com/PJqP07m.png
(Old icon in screenshot, redid it again just before release because it didn't look too good on belt...)

Some error i see with larger prime number like 13. It's still acceptable though imo and just a little balancing issue. You might see it give 3 gears when 3.4 is expected, or something similar. It's close enough, and as long as you use default settings or multiple of 5 compress ratio it's fine. Even many other numbers are fine, divisibles with 2,3,4 as well should be. ("Fine" meaning completely without rounding error.)