When placing a slab on top of a honey block, in this case polished blackstone slab, the honey block effect of not being able to jump and the movement slow goes through it and the effects are as you were standing on the honey block itself.
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update, it has the same properties with ice as well.
Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-1127, which has been marked as Works as Intended - this is an intentional game feature. If you have a different opinion, please visit the Feedback website.
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