I have found a bug with the recent version:
concrete-productivity: infinit research followed by 1

I am not able to find nor repruduce this bug in Factorio 2.1. Could you be more specific?

This log shows the error. I try to find out which mod combination it actually triggers.
https://pastebin.com/VZLn8BR5
EDIT: Here is a reduced log with fewer mods but still with the error.
https://pastebin.com/tL8tpmru

https://pastebin.com/BXVqBm07
My suspection is that it has to do with Paracelsin.
https://mods.factorio.com/mod/Paracelsin
Tell me if I can be more helpful with tracking down the bug.

I've found the bug. Paracelsin already implements a recipe for concrete productivity, whose name is the exact same as mine.

I've renamed the prototype (the research) to be a bit more unique and I've implemented a migration protocol to preserve existing saves. This should fix the issue.

You sould tell the developer of Paracelsin to rename their prototypes aswell, into mod-specific naming conventions, such as:

"Paracelsin-concrete-productivity"

to avoid compatibility issues.

Thanks for the report!

Thanks for the fast reply and fix. As a mod author myself, I really appreciate your effort.