OpenGL renderer misbehaves when dealing with opacity
I don't really know how to explain, but it looks like the GL renderer is not considering opacity when rendering animations. Before and after animating, the opacity is respected.
This can be visualized here (keep staring the first and second tasks' checkbutton): https://cloud.gnome.org/s/P82M3triiARWgbf
The Vulkan and the Cairo renderer do not suffer from that.