Hi Kevin-
Welcome back to the community and thanks for posting! I would recommend taking a look through the main community post announcing the upcoming SmartThings API Limit change as it has more details about the change including details about how to check your usage and patterns to reduce usage.
The Over Limit email should currently include a note indicating that usage is not being enforced at the moment. I enabled the usage notification this month as another notification to ensure anyone who missed the previous one-off communication was aware.
This allowance is not currently enforced. Your Rules are not blocked; this warning helps you prepare.
Make sure to check the Usage view linked from the notification and described in the community post above. You can access it from your Rule list by tapping the … in the top-right corner and selecting SmartThings Usage. That’s the best way to understand your usage, including which rules are contributing to usage - especially switching between Current Month, Last 7 Days, and Latest Day to get a feel for if changes you are making to rules are reducing usage as expected.
I took a quick look and it seems like more than 98% of your usage is from a single HVAC Temperature calculation rule which is presumably triggering very frequently and the call to set a SmartThings Virtual Temperature device is driving the SmartThings API Usage.