Hole Drill Sizes >1mm in Eagle?
You haven't mentioned which version of Eagle you are using, but I had a quick play with Eagle 9.0.1. Changing from 0.8 mm to 1.8 mm in 0.1 mm steps produced a range of centre definitions (bow ties, Ys, stars) until it reached the final slash. It doesn't mean anything in particular, as far as I know (many boards made), so don't worry about it. Double check your Gerbers if you are worried :)