yellowsoar
Ref for PU:
<https://en.wikipedia.org/wiki/Running_track>
Ref for acrylic:
<https://en.wikipedia.org/wiki/Hardcourt>
Can't find relevant information to this sport field about the surface. But I realized that, in general there is a high chance to be acrylic after I modify the surface. So if anyone else found it's actually PU, please provide more evidence here or create a new OSM note.