@marcan the reason GNOME doesn't enable fractional scaling by default is that none of the solution for XWayland was considered satisfying until now. There is more to it, but that's one of the main issue.

We are looking into using rootfull Xwayland to solve the problem.

See "Are we done yet?" in https://ofourdan.blogspot.com/2023/11/xwayland-rootful-part-2.html but I recommend reading both parts.