After the update for 1.18 placing some blocks from schematic using the Easy Place mode causes "ghost blocks" to be placed. So basically places the block only client side.
I know this issue applies to stairs and leaves, but might be more. I didn't do much reaserch.

Are you on a server? What type of server? You may need to change the Generic -> easyPlaceProtocol option depending on the server you are on:

• Set it to v2 if you are on a server that has CarpetExtra (or otherwise supports the Carpet Accurate Block Placement protocol)
• Set it to Slabs only if you are on any Spigot/Paper server variant (or even any server that doesn't support the Accurate Block Placement protocol)
• Set it to v3 if you are in single player, it has the best support for different block types