Welcome Kymco Owners!
This hole is supposed to be an indicator (by showing a drop ore more) that your rear axle/transmisson oilseal is worn out. Means wheel off and renew. Axlebearings in your swingarm are to be checked too and if neccessary, changed.
I saw a little leak from the rear axle i dont know if its coming for the hole or its coming from the transmission seal.https://youtu.be/gh4WTf_HiHo this is something serious? But the way what is that hole? This is after cleaning. Before its worse little worse