The bug

When wardens are digging, either when spawning or when leaving due to inactivity, they can create particles for the blocks they're not colliding with. In addition, these particles can be created in midair instead of only at the positions of the blocks they're colliding with.

How to reproduce

My setup is janky, but here's a rough guide. Since this was a superflat world, a command block clock was used to constantly get rid of slimes to prevent warden distractions. and delaying the experiment.

1. Create a 3x3 platform out of blocks. One of the corners of the block must be an impulse command block
2. Set the command block's command to tp @e[type=warden] ~0.125 ~1.5 ~0.125, changing the signs (positive or negative) before each 0.125 as neccessary
3. Place carpets atop the eight outer blocks of this platform
4. In the middle of the platform, place a full solid block
5. Create a redstone clock that powers the impulse command block every second or so
6. Place a sculk shrieker, using commands or debug items to make sure it has "can_summon" set to true
7. Trigger that sculk shrieker until a warden spawns naturally
8. After it spawns, wait a minute (in creative as to remain undetected) until it gets bored and leaves

Expected results

The warden, which appears at the very corner of the top solid block but still colliding with it due to where the command block teleports it (provided you've tweaked the command accordingly), would only produce the particles of the block it's colliding with, and those particles would only be produced at that block.

Actual results

The warden can sometimes produces particles of the block it's above but not touching (i.e. the carpets). More prominently, the particles the warden generates aren't created at the block it's colliding with.