iPhone strobe flashes a few times with a strong, short sound

I posted a question 6 months ago about a similar event with my iPhone 7.

https://discussions.apple.com/thread/254641194?answerId=258672081022#258672081022

Now, I've got a new iPhone 14 Pro updated to the lates OS and it happened again. A few times flashing strobe light for less than a second and a very strong digi-digi-ding type of sound. As before, no indication on the screen what had happened. The phone was resting on the table. I have an Apple Watch, but did not use its 'locate my phone' button. And later, when I tried, the sound was different and there is no flashing light for that function. So, Apple Watch is NOT the solution.

This really freaks me out. No one else has access to my Apple ID, so its not that someone would have initiated a "find my iPhone" service. I tried that one too, but the sound & behaviour of the phone differs from the one I experienced.

Any thoughts on what/why/who/how etc.?