This advice might be 'newer' but it is not necessarily the absolute truth....and appears to be aimed at the commercial poultry industry.This advise isn’t using newer recommendations for chicken keeping.
I saw nothing about about this^^They have found that exposure to 60F during egg cycle causes egg yolks to have a toxin.
Is this the study you were trying to cite @Dianemarie ?modernpoultry.media/cold-temperatures-can-have-severe-
https://modernpoultry.media/cold-temperatures-can-have-severe-consequences-for-poultry-health-and-welfare/?mp=1738871623664