very high ping for no reason

[wary palm]

when i join i get 20k ms for no reason server and network speed are completely fine

also the chunk load speeds are very bad

constant lag spikes

[sleek thorn]

whats the ram values doing at the top right of the F3 screen when you get the lag spikes vs before/after?

in the top left of the F3, what do you see for TX, RX, C, E, and P values?

[wary palm]

its jumps between 5000 and 3000 total allocated is 8000

[sleek thorn]

I assme thats the ram values. at the lag spike, are you seeing ram usage drop from a high% value to a lower % value?

[wary palm]

after the ping lowers it goes from 5000 to 3000

ram usage

[wary palm]

do you know how to fix it?

[sleek thorn]

you could try using spark to identify the lag spike cause.
in F3:
Look at the TX and RX values to see if there are a ton of packets being received or sent
look at the C value for chunks. see if reducing view distance helps
look at the E value for entity count. this should be relatively low
look at the P value for particles. a massive amount of particles can quickly increase latency or cause lag spikes

after verifying that none of those are significantly increased, some things to try:
try using ZGC instead of G1GC or using Meowice's java arguments
test in a super flat world in single player

to rule out network issues:
assuming you are having issues on a server, test in single player
test on a local server running on the same pc as your client (using 127.0.0.1 as the server address)

[wary palm]

tx 30 rx 50 then i get disconnected

[peak crane]

Are you self-hosting or using a server hosting service? If the latter, it could be an issue on their side, and I'd suggest contacting their support.