The bug
Fences in mineshafts generate like they're connected to air. The bars remain until the right block state is updated. In Villages the fences in lamp posts don't connect to nearby blocks. Stairs in end cities are sometimes not connected.
Seed and coordinates for 1.13-pre5
-7851782326726061748
/tp -10 36 22
Structures found to be affected (list is probably incomplete):
Mineshafts
Villages
Strongholds
Igloos
Woodland mansions
End cities
Witch huts
Shipwrecks
Linked issues
is duplicated by
relates to
Attachments
Comments

These coordinates are just an example. It appears in other mineshafts too
Can confirm.
[media]

Not sure if that's the same problem, but here's a similar effect with the fence in a village
[media]

Attached some screenshots from a village on seed -4993882290258736180.

Also affects chorus plants in The End (only generated ones)

For chorus plants see MC-124916.

in woodland mansions: MC-132322

That was marked about four days ago.

seem like it's still in game https://gyazo.com/359de6ecc0e61e6a1ee4a2a8b65aea1f

Correct. Still present in MC 1.13-pre6.

it is fixed with me

@@unknown Did you test every structure? Because I'm still getting this bug with fences in shipwrecks, but not in mineshafts.

Can confirm fixed for 1.13-pre7 per seed and location provided. Also did some testing with other structures in the same world, which seem fine to me. Tested were mineshaft, stronghold and shipwreck. (Sorry for the double ping)

Could you provide a new seed & coordinates (since I cannot reproduce in 1.13-pre7)?

I cannot reproduce
I cannot reproduce.