The Bug:

Sculk sensors are not activated upon silverfish or endermite moving along the ground.

Steps to Reproduce:

• Summon an endermite or silverfish.
  →  Notice how the sculk sensor does not activate, upon them moving along the ground.

Additional Information:

Please note that the sculk sensor will detect the endermite/silverfish changing y level. In other words, climbing or falling down blocks. Quote from the 20w49a Changelog, "A vibration is anything that causes physical motion". I would definitely consider this as physical motion, as these mobs are physically moving along the ground.