[Will be solved in 2.0.11] PNG w/transparency breaks in SDL 2.0.10 but works in SDL 2.0.9

SDL Development
9

This issue is now resolved (very quickly) by an SDL developer (Sylvain).
The fixing commit is here: https://hg.libsdl.org/SDL/rev/0c66be754e29
And it is scheduled to be included in upcoming SDL 2.0.11.