The bug
When a player is on soul sand/soil normally, they can jump and retain the soul speed effect. However, if a slab (or potentially other partial block) is placed on top of the soul sand/soil, jumping will switch out the soul speed effect momentarily, which results in jerky field-of-view and movement.
This may be intentional behavior, as the player is more separated from the soul block with a block above than just the sand/soil itself, but it seems quite unnatural nonetheless.
Related issues
is duplicated by
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Can confirm in 20w51a.
Can confirm in 21w03a. Feel free to use the following command to make reproducing this much easier:
/give @p minecraft:leather_boots{Enchantments:[{id:"soul_speed",lvl:3}]}
Can confirm in 21w05b.

Confirmed for 21w11a
Can confirm in 21w13a.
Can confirm in 21w16a.
Can confirm in 1.17.

Confirmed in 1.19.2
Can confirm in 1.20.6 as well (the previously stated 'blocked' links are new to 24w18a)

can confirm fixed in 24w20a
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