Distinguish OSM data overlay

[geohacker]

From @LanesGood:

Consider using a distinct fill pattern (lines?) or area outline for OSM data to distinguish from user-drawn samples.

Here's a library: https://github.com/teastman/Leaflet.pattern

And an observable on doing this with svg directly: https://observablehq.com/@clhenrick/leaflet-pattern-fills

Leaflet.Pattern is likely an acceptable and straightforward way to implement this.

I would advocate for a stripe pattern overlayed on the selected feature.