I have also noticed that probably Europe and the US vote somewhat differently on at least some of my comments. But I think that's a separate pattern from the tendency for some of my comments to be immediately downvoted and then voted back to neutral.

It tends to be certain kinds of comments and unlike almost everything else about HN, I am usually not surprised by that pattern because I tend to expect it for certain topics or certain types of observations that I sometimes make.

I have a really poor ability to predict which comments of mine will do really well.

I have a really poor ability to predict which articles I submit will do really well.

I have a reasonably good ability to predict which comments will be promptly downvoted and then get corrective upvotes.