The bug
Throwing eggs and snowballs though cobweb just hits it and breaks. Shooting arrows and tridents through cobweb does not slow them down, they act as if they were being shot through the air.
Related issues
Comments

Wouldn't an arrow slice through cobwebs though? I think this may be intended but we'll see what Mojang says.
Confirmed for 15w47b
Changed the behavior of all the throwable items to ignore none solid blocks (ie : Tall grass and such) and to get "stuck" when hitting a cobweb.

Confirmed for 1.12.2 and 17w43a.
Confirmed for 1.12.2
Is already marked as affected.
Confirmed for 1.13.1.
Confirmed in 1.16 Pre-release 2.
Confirmed in 1.16-pre4.

Affects 1.16 pre5
Confirmed in 1.16-pre7.
This issue seems to be fixed in 20w48a.
I think this isn't fixed yet. Could anyone confirm?
Can confirm.