This mod removes or optionally reduces the pop growth requirement penalty. (needing 250+ pop growth to spawn a new pop) Extra versions also reduce or remove the colony abandon influence cost.
This mod has many versions for all combinations of above listed features.

What exactly does this mod change and how?
Changes the pop growth and pop assembly penalty to either 0.00 (no penalty) or 0.1 (a fifth of the original penalty)
So without this mod even though you might have something like 12.0 pop growth per month instead of only needing 100.0 pop growth to spawn a new pop, in 3.0 you now need anywhere from 150 to something as high as, or even higher than 500. this has made it so your pops basically never grow.
This mod fixes that.
There are also optional file versions that changes the colony abandon influence cost to 0 or 40 ( a fifth of the original cost
Finally this mod raises the maximum pop number for an empire from 500 to 9999.
(I don't know what absolute moron decided to add this in the first place.)
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Installation and Uninstallation

For Manual Installation: Just download whichever file version you want, unzip, the frag the "common" folder into the stellaris game folder. Then click replace "00_defines.txt"  when it asks if if you want to replace it.

For Manual Uninstallation: Do the same process as above for the manual installation but use the "Original Files for Uninstall" folder. You can download this separately in the files tab. Just overwrite the "00_defines.txt" like for the install process and you're done.
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Compatibility:
This mod only changes the file 00_defines.txt" so anything that also affects this will likely conflict. Anything that doesn't shouldn't conflict at all.
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FAQ
Does this mod also affect assembled pops (robots and clone vats)?
Yes, in the exact same way with the exact same ratios and numbers.
Is this mod Safe to install or uninstall mid playthrough?
Yes, for both installing and uninstalling, at least on my game when I tested it.
Why is this mod called Anticast
Because it removes the castration on the pops to they can actually re-freakin-produce.
Also because it's easily remembered ... but mainly the first part.
What about the Max pop growth change?
This I'm unsure about because with the new changes I've never gotten to 500 pops but supposedly there is a maximum amount of pops or empire can have before all pop growth stops completely. I chose not to remove this number entirely because i don't know if it would cause any issues so I just changes it to 9999.
What version is this compatible with?
Stellaris 3.0 Nemesis. This might be compatible with later versions but I can't guarantee it. This will NOT be compatible with any earlier versions before 3.0. 
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Permissions
Feel free update this file for newer versions of the game, or re-upload this mod on other websites like steam workshop, as I don't upload on other sites.
No credits needed. 
Basically I don't care just as long as players can get this mod to fix this completely boneheaded decision by paradox. 
I mean what in all conceivable damnation were they thinking?!