I think you are saying that all three scripts, which are on three different platforms, started having intermittent email delivery problems at the same time. I find it hard to believe that the failures are anything to do with your scripts. If one had gone wrong, then possibly; two would be a puzzling coincidence but all three failing really smells of some external change. I would ask the relevant bods to look in the change logs to see what altered on 14 April, 2020 and would also ask which jobs, if any, kick off at around midday. I would not start altering the scripts or their dependencies until I had answers to those questions as you might be introducing problems into scripts that aren't actually broken!