UI Scaling is in state of neglect
Customers have been reporting the bugged UI scaling for years and no response. The fact adobe products don't scale properly on a 4k monitor is a glaring issue.
Adobe support will recommend you adjust your monitor resolution and/or the OS scaling settings - both of which cause problems elsewhere, outside of adobe products.
The burden should not be on the user, nor the OS.
Writing this as a new customer who installed Photoshop and Premiere to find it unusable out of the box.