The following screenshot is taken from the spawn area of a new world (more or less my starting location):
Spigot version: git-Spigot-a19903d-5b74714 (MC: 1.16.4) (Implementing API version 1.16.4-R0.1-SNAPSHOT)
Other plugins: worldedit, worldguard, luckperms, floodgate (geyser extension to allow bedrock players) and four own plugins, none of them messing with the world generator.
After removing all other plugins and regenderating the world (by deleting the world folder), there were no floating trees, but there also was no water in the spawn area. Other trees in the water (at other locations) were not floating.
After another new world - in fact, a whole new server instance with no plugins except EWG and also upgrading the the newest spigot version (git-Spigot-628435a-768d7fc) - I got floating trees again - again above water, and again only in the spawn area:
Note that the coordinates of the second screenshot are around -30,-160 and I found no other floating trees in the area. There were some at 0,150, which were all properly on the ground (and not in or even above the water).
So alöl floating trees I found were directly next to the position of my first spawn, I didn't find any further away from that. Also, they were always above or close to water.
EWG 8.1.43 generates floating trees.
The following screenshot is taken from the spawn area of a new world (more or less my starting location):
Spigot version: git-Spigot-a19903d-5b74714 (MC: 1.16.4) (Implementing API version 1.16.4-R0.1-SNAPSHOT)
Other plugins: worldedit, worldguard, luckperms, floodgate (geyser extension to allow bedrock players) and four own plugins, none of them messing with the world generator.
After removing all other plugins and regenderating the world (by deleting the world folder), there were no floating trees, but there also was no water in the spawn area. Other trees in the water (at other locations) were not floating.
After another new world - in fact, a whole new server instance with no plugins except EWG and also upgrading the the newest spigot version (git-Spigot-628435a-768d7fc) - I got floating trees again - again above water, and again only in the spawn area:
Note that the coordinates of the second screenshot are around -30,-160 and I found no other floating trees in the area. There were some at 0,150, which were all properly on the ground (and not in or even above the water).
So alöl floating trees I found were directly next to the position of my first spawn, I didn't find any further away from that. Also, they were always above or close to water.