The bug
Interacting or breaking certain multi-blocks as non-op player in the spawn protection causes desync.
Affected blocks
Right-clicking wooden door
Breaking double chest
Breaking tip or middle piece of
Kelp
Twisting vines
Weeping vines
Dripstone
Cave vines
Breaking piece below top piece of big dripleaf
Breaking parts of a redstone wire
Reproduction steps
Start a server
Op any player other than you (from the console) to activate spawn protection
/op Notch
Join the server and try to break or interact with multi-blocks listed above within the spawn protection
❌ Either the broken block or the other half does not update correctly
Related issues
Attachments
Comments

There have been a lot of tickets about this already, however they have been resolved as invalid iirc (as in "cannot interact with blocks in the spawn protacted zone"). Might make sense to have a ticket for the desync only though.

Can still reproduce in 20w51a for some blocks and have updated the report accordingly.
However, cannot reproduce anymore for breaking doors or beds.

Affects 21w05a
Also affects big dripleaf and cave vines. small dripleaf seems unaffected.
Can confirm in 21w18a.
Can confirm in 1.18.1. This seems to affect all blocks that can have their block states altered depending on nearby blocks, for example, iron bars, glass panes, tripwires, double chests, stairs, etc... I've provided a video that demonstrates this behavior occurring for visual purposes.
[media]Can confirm in 1.18.2.
This issue was present in 1.18.2, but no longer occurs in versions above or equal to 22w11a. With that being said, this issue has been fixed in 22w11a.