Green shapes blue line

[David263729270wgf]

Adobe Photoshop 23.5.1  Mac OS Monterey 12.6

Create any green shape.

Shape should be all green but there is a thin blue shift/line at the bottom.

It's not terrible under normal circumstances but if you do anything to enhance the edge, like "Bevel and Emboss" which I would like to do it becomes intolerable.

[TheDigitalDog]

If I download the image you provided, I see a fully green square, no blue. 

This may be a display issue on your end if, indeed, I'm supposed to see any blue line in that document. 

First, try disabling GPU in the preferences (Performance tab). Any better?
If not, go to Preferences > Technology Previews... and check "Disable Native Canvas" - then restart Photoshop. Better?
If not, recalibrate and build a new ICC display profile; the old one might be corrupted.
If you are using software/hardware for this task, be sure the software is set to build a matrix, not LUT profile, Version 2, not Version 4 profile.
If turning OFF the GPU works, it's a GPU bug, and you need to contact the manufacturer or find out if there's an updated driver for it. 
Also see: https://helpx.adobe.com/photoshop/kb/acr-gpu-faq.html
https://helpx.adobe.com/photoshop/kb/photoshop-cc-gpu-card-faq.html