See https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/1902 and https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/1903 Since WebKit has (multiple) copies of the same code, it has the same issue.
Created attachment 403192 [details] Patch
Happens in GTK4 as well with https://bugs.webkit.org/show_bug.cgi?id=213791
Committed r263838: <https://trac.webkit.org/changeset/263838> All reviewed patches have been landed. Closing bug and clearing flags on attachment 403192 [details].