According to the release notes for 20w49a "...some motions that are undetectable to sensors by sneaking", these "sneak friendly vibrations" include:

throwing/shooting projectiles

Tested on a new world to be safe.

Firing an arrow that is ON FIRE from a bow (enchanted with flame) while holding SHIFT (crouch) causes the sculk sensor to be triggered @ comparator level 9 (not even 'Projectile Shoot' trigger ).

Things to NOTE:

Level 9 considers "Hit Entity", but the arrow does not hit anything nearby, the arrow is shot several chunks away.

 I shot the arrow while sneaking BEFORE enchanting with Flame ... and the Sculk sensor was not triggered

Likely relates to: MC-207384