It's either a remarkably shoddily installed load spreading plate / eyebolt or a repair - If it was for liffting there would have been a symmetrical set of at least two, and the hole would (should!) have been a bit(!) rounder. Surrounding Gelcoat hints at impact / repair as well.
When I got mine it had 8 M10 holes (4 u-bolts), one in each corner (so to speak!) which thankfully seem to have been sealed & kept maintained with fresh sealant every so often, as the hull was dry in the area. The main down side was that the threaded ends of the bolts poked down about an inch & a half, when I removed the stern ones & filled the holes I got an extra couple of knots out it!
Holes through the hull are OK, IF you seal them properly and don't mind the extra drag....