In a resource pack, if a vanilla block uses a different vanilla block model using the "blockshape" component in blocks.json, some blockshape IDs will work as expected - but other blockshape IDs can cause unexpected behavior, including strange shading and loss of tints.

For example, changing leaf blocks to have another blockshape may cause them to lose ambient occlusion and have flat shading, in addition to losing their green tint ("scaffolding" is an example of a blockshape ID that works as expected with leaf blocks, while "cactus" is an example of one that removes the green tint, as shown in the attached image). Further, adding the cactus blockshape to a solid block, like a jukebox as shown below, will cause strange dark shading to occur. 

I cannot determine any correlation with which blocks do and do not work with which blockshape IDs. I have found that the blockshape's original block lacking ambient occlusion is not a determining factor - as scaffolding, for example, does not have ambient occlusion - yet the "scaffolding" blockshape does work with leaves, and does not cause the shading issues.

This really holds back a lot of creativity and possibilities in texture packs, so I hope it can be resolved. Ideally, changing the blockshape should only change geometry, and not other properties like ambient occlusion or how tints work.