Hi tiredmonk,
I understand you are using flow with a SharePoint list, as the error started after the flow was created, we’ll suggest you post in Microsoft Power Automate Community for expert assistance. This is a specific channel related to issues with Power Automate.
The reason I request you to post a new thread is that in Answers forum, we have limited resources and very little knowledge about Power Automate flow and in Microsoft Power Automate Community, you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction.
We appreciate your understanding.
With Sincerest Regards,
Neha