This ticket concerns an unannounced model change from 1.8; as said change is unannounced I've reported it as it may not be intended. I personally prefer the result of this change and would like to see this ticket resolved as Works as Intended, however such a decision is ultimately up to Mojang. More information below.

The bug

When hoppers were converted over from hardcoded rendering to block models in 14w17a, this resulted in changes to their appearance, which may not have been intended. In partcular, the interior of the hopper gained directional shading where it was previously lit the same everywhere inside.

Since Bedrock Edition has yet to convert blocks over to models, this technically also constitutes a parity issue (although the change in question happened considerably earlier than the 1.15/1.14 deadline).

This is not to be confused with MC-129826, another flower pot model shading issue which is DEFINITELY a bug.

How to reproduce

1. Place a flower pot
2. Pay close attention to the inside, and note how it appears darker or lighter on different sides
3. Repeat this test in 14w11b or earlier
4. Note how the inside appears equally lit from all sides in these versions

Expected results

The equally lit inside would remain so in current versions.

Actual results

It appears shaded differently on each side in modern versions.

How to fix

If this is determined to be a bug, the fix might be a tad complicated: the interior faces would need to be split off from the current cuboids and given their own, dedicated elements, with these elements given a "shade: false" line to prevent shading.