Bug

Never put your piece on one of the four squares on your top right.  My clock ran out because the queen wouldn't move (inside red circle).

I don't think the lag cares about what square you move into...

It's not because of lag. The mouse pointer changed from "click" to "select" around those squares. (I'm not sure I could explain it correctly)

Isn’t that because the settings appeared around those four squares?

That's what I think too.

It's called changing your browser zoom. Control +/- changes the zoom. This is not a bug.

The new tabs design should make this no longer be an issue