The Bug
The subtitle for picking up a Tadpole with a bucket is just the generic "Bucket fills" subtitle while picking up other mobs with buckets like fish and axolotl have unique subtitles
Reproduce
Turn on subtitles
Spawn a Tadpole
Pick the Tadpole up with a Water Bucket
Look at the subtitles
Observed Result
The subtitle said "Bucket fills"
Expected Result
A subtitle that would reference the tadpole being scooped up
Can confirm. This issue is inconsistent with axolotls and fish.