SeedcrackerX VS SeedCracker

Actually there is a way. https://github.com/19MisterX98/SeedcrackerX this dev made it that works on servers. Just need the user to find structures like. Wrecked ships and stuff and it’ll start cracking the seed and it will lag your game for an bit

I an using https://github.com/19MisterX98/SeedcrackerX On a 1.20 paper server that uses different seed for each dimension. I manager to crack the overworld seed, but struggling to crack the nether seed, I only got warped fungus turned on, in 1.20 I visited multiple warped fungus biom and nothing so I put the settings at 1.16.4 and still nothing.

this tool is easy to use to get the seed

You can use seedcrackerX: https://github.com/19MisterX98/SeedcrackerX

seedcrackerx by 19MisterX98

1.19.4 version does exist

If you don't respect this, you can use https://github.com/KaptainWutax/SeedCracker

Custom code, usually. KaptainWutax made a program a few years ago which can crack seeds just by scanning the world. When seed cracking, though, you are looking for certain features which can rule out many many seeds very easily. For example, finding specific dungeon coordinates and mossy cobble patterns can narrow it down dramatically. For this process, you need not scan that much since it's some simple maths applied to not that many blocks and not checking very many times.

Im not an expert but cords are needed or at least if you want to solve it in any time. you say you play on that SMP so maybe use seedcrackermod but KaptainWutax. It is a fabric mod that searches the world for structures like shipwrecks and once you find 5 of them it can crack the seed within minutes or even less (depends on your gpu)

Otherwise, I found a mod that will calculate a server's seed but you have to actually be on the server; most of the actual tools seem to be private, most likely due to security concerns as stated above.