Server Out of date (Cracked)

does anyone know how to fix this? i am currently in 1.15.2 and server installed is 1.15.2 but it's saying that the server is out of date

nvm i just use the address that pops up in the message of the server although it gets annoying from the fact that it changes everytime

My username is actually the name i'm using at this website right now JohnErick_091