Using mc 1.20.4
Server using Minestom(Velocity) and it should normally work.
Mod Version Lite: 0.17.2 Mal: 0.18.1
I'm playing on a server called mineplay which combines ROBLOX's and MCs servers and other people can use it but for some reason my version hates mineplay and refuses to place blocks. these blocks become ghost blocks and the owner never made the server reject litematica. these blocks are in the air and I'm using easy place. What's wrong?

The most important setting for whether you can place any blocks on a server with the Easy Place mode is the easyPlaceProtocolVersion config. If the server doesn't specifically have a mod to handle it, then you should keep it at None, Slabs Only or Auto. I see you have it at None, so that's fine. (If you force it to Version 2 or Version 3 on a server that doesn't have a mod to handle the "accurate placement protocol", then you will only get ghost blocks in 1.18.2 or later for any blocks that have a direction property or a top/bottom property, and the server console shows "Rejected ItemUse packet" for each click with such blocks.)

So then that means that the server must simply reject any clicks on air blocks. The Easy Place mode currently always clicks on the target position's air block, even if the block is next to another block. You can also test this with Tweakeroo's Flexible Block Placement with the offset key/mode. That also clicks on the target air block.