Simple. Break the top of tall grass and see the particles.
The particles that appear when you break a two-block tall grass or flower (fern, rose bush, ect) are broken and misplaced
Double Grass shows Peony top when bottom broken
When breaking tall plant/grass from bottom peony appears, and if broken from bottom to top in quick succecesion sunflower particles appear.
Graphics/ Items bugs- Plants
The top block of a two-block plant temporarily becomes a peony/sunflower upon placing a block in the bottom
Breaking two-block plants shows wrong breaking particles