I checked our server using this mod, and technologies processing-unit-productivity-2 and processing-unit-productivity-3 are still present. Can you confirm the mod setting 'Push back infinite research' is still enabled?
Double-checked and all my settings are still checked for hard tech tree. Also the affected infinite techs are no longer parented to the Infinite Research technology.
If you'd like I can send logs and my save game? Where would be the best place to upload?
I'm not playing Krastorio so I can stick to 1.3.6 for now.
Noting here from discord discussion that I think this is caused by Finite Repeatable Technologies now loading before Hardcore tech tree. I've submitted a bug report asking for finite repeatables to add hardcore tech tree as a hidden optional dependency. https://mods.factorio.com/mod/finite_prod_techs/discussion/6944958f0db5cdb8ca8a229d