The programmer art pack still has little inconsistencies that are extremely frustrating. Buckets with new mobs have the new texture but when it’s emptied, it goes back to normal. Nether grass variants are jarring to look at when trying to mesh with regular netherack. Small things like that that make the game feel less immersive because of the lack of compatibility with newer versions of minecraft. The programmer art doesn’t need to have an original texture for every single new item and block that is added, but making changes to these little quirks would go a long way.
Related issues
Comments

Thank you for your report!
We're tracking this issue in MC-169889, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Hello,
Thanks for reaching out! This appears to be more of a feature request rather than a bug. While it could be deemed as unintended, the current behavior is in line with the current mechanics of the game.
If you would rather this be improved or otherwise different in future patches, I'd recommend providing your feedback on the Minecraft Feedback website at:
https://feedback.minecraft.net/hc/en-us
The developers regularly review community suggestions, and this would be the best way to get it considered.
Best,
Woo