Using a resource pack that changes the model of "overfilled" bundles (using the predicate filled>1.0) no longer works in 21w20a.
1) Create a world in 21w19a and give yourself a filled bundle, and an "overfilled" bundle
2) Enable the attached resource pack
3) Note that the items have textures
4) Create a world in 21w20a (or upgrade that world), and the filled and overfilled bundles have the .