What Icon Is This?

It's a sideways heart

 

Or a very blocky letter "L". Is this a notification icon or an icon on a homescreen? These days notifications are usually monochrome, though there are still a few that violate that guideline.

The truth is that there are literally millions of apps out there, so if a reverse image search doesn't find it (I assume you've tried, but it doesn't bring up anything for me) it's a real long shot asking this question, because unless it's a common app, as they sometimes are, it's unlikely anyone will have seen any particular icon before.

I know you probably don't want to ask the person in question (because people asking this invariably don't), but it may well be your only hope of getting a definite answer.

 

Heart type notification on a Xiaomi phone. Could be Xiaomi Health or Mi Fit?