I have this happening as well.
But, I like my stuff small so I use it like this.
Although, I'm seeing the other two guys with issues are using 1440p, same as me.
This makes me think the option for high res, is meant for 4K displays and that's why it's too big when activated in 1440p.
So from what little knowledge I have, this means the UI would need some sort of conditional scaling based on the user's resolution maybe?
I realize this could be a lot of work based on the number of possible resolutions people can run the game at, but since the pixel fonts and such have been dropped, there should be a way...
For reference, here's my screen:
