4K 60hz external monitor feels laggy resolution jumps to 6016x3308

Hi,

I don't know what has been changed but for some reason parallels on a 4K external monitor is feeling laggy.
I've checked the resolution and refresh rate and the resolution and refresh rate is 6016 x 3308 60hz.
60hz is OK since my external monitor only support up to 60hz under 4K under DisplayPort 1.2 (HDCP 2.2).

My parallels settings under graphics are "best for external display".
If I change the Windows VM resolution to 3840 x 2160 the main VM screen is shrinked and I don't get a full screen, when I double click the VM title bar to enlarge to a full screen the resolution is changed back to 6016 x 3308 and it's getting laggy.

What am I doing wrong ? I'm using parallels for 2 years now and it wasn't like this.