See attached screenshot.
MC-127038
Sea plants generate directly under or cut off by ocean ruins
Resolved
Fixed
0
[Mod] redstonehelper
(Unassigned)
Unconfirmed
Minecraft 18w10c, Minecraft 18w10d
Minecraft 1.13-pre3
Retrieved
Swam around for a while looking at multiple ocean ruins and I haven't been able to reproduce. Pretty sure this has been fixed.