Hello PlantUML team,
To continue to test on https://forum.plantuml.net/11491/backgroundcolor-transparent-doesnt-empty-group-deployement.
We observe this issue, from 1.2020.11-12, for PNG output, for some rounded elements (database, queue, storage).
That is OK, with colored BackgroundColor:

[Click to see...]
But with BackgroundColor transparent, that is KO (on 1.2020.12: we observe no shadow or incorrect shadow):

[Click to see...]
Regards,
Th.