Internal Alert Recipients Automatically Disabled

We have two separate clients that are using internal alert flows where their individual emails keep getting automatically disabled from the recipient list. I am also a recipient on both flows and my email has never been disabled. One flow has been set up for about 7-8 months and the account owner’s email has been disabled at least 3 times, and the other client’s has been disabled once in the 3 months his flow has been set up. 

Each time I have to go into the flow and trigger (resend) the consent authorization for them which then reactivates their email, until it doesn’t work again at some point. Neither of them are actively unsubscribing from these notifications either, since the forms tied to the flows are imperative to their businesses. 

Any idea why their emails keep getting disabled?