Hello Dave,
Thank you for posting to Microsoft 365 and Office Community.
According to the description and the screenshots you are facing an issue with Power Automate “Get an email reminder” flow. Apparently, there is an error in one of your flows.
You may follow these steps to find an issued flow:
- Check in the mail the time to find when the error executed
- Open Power Automate. https://powerautomate.microsoft.com/en-us/
- In the left menu select Monitor and then Cloud flow activity
- There you get an overview of the flows in your environment and the time they were executed. Check the flow Status that was running at the time from step 1 if there are any errors

You may need to edit or delete the issued flow and recreate it again.
As you are encountering an issue with Power Automate flow, to make sure you get an expert help I kindly suggest you to post to Microsoft Power Automate Community - Power Platform Community site. The members and engineers in this community have more resources and test environment to find the related answer to your concern.
Best Regards,
Igor