Does the Apple Watch SE send you irregular heart rhythm notifications

No, these things are not published, but I would imagine it corresponds to the daily heart rate checks every 10 minutes or so.The link says

"If you receive a notification, the irregular rhythm notification feature on your Apple Watch identified an irregular rhythm suggestive of AFib and confirmed it with multiple readings.

If you have not been diagnosed with AFib by a physician, you should talk to your doctor. If you have been diagnosed with AFib by a physician, learn how you can track your AFib History on Apple Watch."

The SE2022 has these notifications as well as the more expensive versions.. The irregular rhythm notification feature on your Apple Watch will occasionally look at your heartbeat to check for an irregular rhythm that might be suggestive of atrial fibrillation (AFib). Learn how to enable irregular rhythm notifications. Irregular rhythm notifications are currently available only in certain countries and regions. You can also find your version of the irregular rhythm notification feature.

I have mine turned on on SE and so far received nothing - I assume that is good news.

Remember that although news stories do give examples of how "lives were saved", nevertheless Apple say the Watch should not be considered a medical device.