I found this thread that fixed my problem.

To summarize: To request a token my frontend or postman (outside of container) will communicate with my container url (localhost) so the issuer will be localhost. But to verify the token, my backend (inside container) will communicate through the container network (in my case http://keycloak:8080). The issuer will then be different and the error will occured.

To fix you need to manually configure the Frontent url in keycloak admin console (in my case http://keycloak:8080)