MBP-16", 2019 Monitor size (inch) is showing incorrect

Hey guys, I recently bought LG 27UP850-w 4k monitor and connected it to my MBP (2019, 16inch) by the USB-C cable that came with the monitor.

But under the "Display" tab in "About This Mac" it is showing as 31.5" monitor not 27". (screenshot attached)

And because of this issue my softwares (photoshop, adobe illustrator, affinity design etc.) showing the dimensions of the artboard canvas sizes incorrect, for example when I create A4 canvas with 300dpi (for print project) and view it on 100% zoom (or print size) it shows it incorrect.

I have searched about this issue online, changed the resolution setting (sys pref > display > scale), tried different settings on monitor itself and no luck.

Does anyone have the same issue?