Migrating from IdentityServer4 to Keycloack

Hi, we are using at the moment, IdentityServer4 and we want to migrate to Keycloak.
The main problem that we encounter is password hashing, IdentityServer4 uses Argon2id and Keycloak uses Pbkdf2 as far as I can see.
How can we migrate without asking the user to register the password.

Thank you!