Update (April 13): The Vivo X Fold was just announced, and its display is exactly what we want to see from the Z Fold 4's.
The rumored Samsung Galaxy Z Fold 4 could be getting a display that's tougher and better quality than last year's model, with the aim of making it better for use with an S Pen.
This comes from leaker yeux1122 on Korean blogging site Naver (via Twitter leaker Dohyun Kim) citing sources in the Korean supply chain. Their post claims that Samsung is working on giving the Z Fold 4 a harder and better quality display than the Galaxy Z Fold 3, all supposedly in the name of making the screen more suited for use with an included S Pen stylus.
Samsung has been previously rumored to be integrating its stylus into the Z Fold 4, after introducing separate S Pen support for the Z Fold 3. It would make for a sensible inclusion considering the size of the display you have to use it on. This plan would also make the Z Fold 4 match nicely with the Galaxy S22 Ultra, which got a Galaxy Note-style makeover, including a built-in S Pen, just last month.
The Galaxy Z Fold 3, along with the Galaxy Z Flip 3 and original Galaxy Z Flip all used Samsung's Ultra-Thin Glass (UTG) material for their displays. Put simply this is a sandwich of glass and plastic that aims to keep the display flexible but tougher than a typical all-plastic folding display.
yeux1122 suggests that these changes may mean Samsung gives UTG an updated name. They suggest the title "Super UTG", which would make sense but is only an example of a possible name, unlike the rest of the leak.
How precisely these display changes improve the writing experience isn't made clear. We can imagine that a harder display would feel better to write on though. The current Fold Edition S Pen uses a retractable tip to avoid excess pressure on the display, which means it doesn't feel like a regular pen or stylus to use. Perhaps the Z Fold 4 could support a traditional fixed-tipped stylus with its improved display.
We are expecting the new Galaxy Z Fold 4 and Galaxy Z Flip 4 models to appear this year around August or so, which is when the last generation of these phones launched in 2021. We've not heard a great deal about either phone yet, but the Z Fold 4 has been rumored to have a wider outer display and an improved under-display camera in the interior display, improving on two weak points of the Z Fold 3.
The Z Fold 4 has also been rumored to also be cheaper than the Z Fold 3 too. Considering the Z Fold 3 retails for $1,800, this would be an even more meaningful change.