This is more for raising awareness for the coming year probably. FoundryVTT version 13 will very likely switch to PIXI V8, a major new version with improvements but also deprecations and breaking changes.
At least one of them will likely affect Sequencer in a way that is not a trivial fix:
Sprites, Meshes etc can no longer have children, only containers are allowed to have children.
Leaf nodes no longer allow children
Only Containers can have children. This means that Sprite, Mesh, Graphics etc can no longer have children.
To replicate the old behaviour you can create a Container and add the leaf nodes to it.
This is more for raising awareness for the coming year probably. FoundryVTT version 13 will very likely switch to PIXI V8, a major new version with improvements but also deprecations and breaking changes. At least one of them will likely affect Sequencer in a way that is not a trivial fix:
Sprites, Meshes etc can no longer have children, only containers are allowed to have children.
As per the migration guide: