When comparing module schemas between Bugfest MG and a new MG deployment, several schemas have differences in their x_set_md and set_x_md_json functions. These functions have differences in the way the date formatting is done for object metadata. This appears to affect all functions of the form x_set_md and set_x_md_json.
I've attached a set of screenshots showing an example from mod-audit. The full list of modules affected is: