When breading the Sniffer it does not account towards the Two by Two advancement.
Reproducung the steps:
Go into the snapshat version in question create a new world or load into a existing wrold with the 1.20 features turned on via the datapack.
Spawn 2 sniffers in creative mode and breed them with the torchflower seeds.
Thank you for your report!
We're tracking this issue in MC-260098, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
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
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki