Recent Versions of GLib Break Dolphin File-Manager's Thumbnailing when Using 'gtk2' Style

Hi, everyone. When the Arch Linux-based package 'qt5-styleplugins' is used and the environment variable QT_QPA_PLATFORMTHEME= is set on "gtk2", or "qt5ct" with its interface set on Appearance > Style: gtk2, the Dolphin file-manager will not create new thumbnails, although thumbnails that were previously created (such as with Thunar, or Dolphin not using "gtk2") will be shown. This problem doesn't occur with the other styles of 'qtstyleplugins'.

I traced this problem back to GLib. The problem was introduced with the following package, and remains in later versions:

glib2-2.62.1-1-x86_64.pkg.tar.xz

The following version and previous versions work properly:

glib2-2.60.6-1-x86_64.pkg.tar.xz

However, using this previous version breaks some (but not all) GTK+ 3 programs.

This is a shame because I use the "gtk2" style for Qt 5 programs, and Dolphin is my primary file-manager. Further, this breaks my Computing Machine desktop-environment theme ( https://www.pling.com/p/1315191/ ).

Can this problem please be fixed? Thank you for your time on this matter!