I was having this issue in 4.19.2.
Judging from some of the descriptions here, this won’t apply for everyone, but just in case it helps somebody: somehow I set my DPI scaling rule in the Project Settings to ‘Custom’ (without specifying any kind of custom scaling rule class). Resetting back to the default (‘Shortest Side’) got rid of the ballooning HZB cost.
It’s not surprising that this broke something. Any of the built-in rules (or correctly referencing a custom curve) would probably do the trick. For what it’s worth, I can repro (if you wanna call it that) on my machine by opening a fresh project, setting the scaling to custom (again without referencing a custom class), and opening the widget editor.