Can't connect solr9 to zookeeper

Question

I have this test in a gitlab pipeline

test:
  stage: test
  image: maven:3-eclipse-temurin-17-focal
  variables:
    ZK_HOST: zoo:2181
  services:
    - name: zookeeper:3.9-jre-17
      alias: zoo
    - name: solr:9
      alias: solr
      command: ["-c"]
  script:
#    - 'while true; do sleep 10000; done'

but this gives the error

Could not connect to ZooKeeper zoo:2181 within 30000 ms

However, if i change to solr8 it works perfectly fine. I just want to make sure that one can connect to the other. What gives? Thanks in advance!

I tried using solr8 and it worked fine. With solr9 nothing works