Walking through cobwebs does not get faster using speed unless you are crouching on slime blocks

If you do /effect give @s speed infinite 254 and walk through cobwebs, a glitch will slow you down unless you are sneaking on slime blocks.

To reproduce
1. Place a floor of slime blocks beneath you
2. /effect give @s speed infinite 254
3. /fill ~ ~ ~ ~20 ~20 ~20 minecraft:cobweb
4. Try walking through the cobwebs.
5. Try sneaking through the cobwebs

Expected results
The walking through cobwebs should be much faster than sneaking.
Actual results
Sneaking is way faster.

Video Below (Recorded on Phone)
1st part is walking, 2nd part is sneaking
https://drive.google.com/file/d/1OSc3ZSwWOyccvbCIz3xmP8JilDS1IX19/view?usp=drive_link