We tested on a few different computers and displays, and the slider border renders a little differently on each one. On some it’s just fine, on others (yours being the most extreme example we’ve seen) it’s uneven.
The problem seems to be with the rounded-rectangle shader’s antialiasing code. It relies on GPU partial-derivative values, which differ surprisingly between GPUs.
Unfortunately there’s not really a good solution at this time. Fiddling with the shader code to make it better on one GPU is likely to make it worse on another. The situation should be better in the future with enhanced vector path support. Since there’s no good action to take at this point (and you indicated that the bug isn’t all that important to you), we’re going to close this bug report.
Thanks for investigating.
I’ve noticed occasionally something similar with text which seems like a slice has been removed horizontally.
If I notice it again I’ll send through, could it be a similar issue?