Only if you installed either our monitoring stack or the upstream prometheus operator

Thanks for your answer. Actually we don't use these. I've been testing these things in some clusters but I see at least some of these crds in all our environments. Then it must be from some helm chart we are using. Actually it's just these in environments where we didn't test anything:

[I] ➜ k get crd |grep coreos
<http://alertmanagers.monitoring.coreos.com|alertmanagers.monitoring.coreos.com>                             2021-08-09T13:28:45Z
<http://prometheuses.monitoring.coreos.com|prometheuses.monitoring.coreos.com>                              2021-08-09T13:28:45Z
<http://prometheusrules.monitoring.coreos.com|prometheusrules.monitoring.coreos.com>                           2021-08-09T13:28:45Z
<http://servicemonitors.monitoring.coreos.com|servicemonitors.monitoring.coreos.com>                           2021-08-09T13:28:45Z

Unfortunately no annotations or labels in the crd and CRs for them. I'll just delete them. Was just wondering where they come from. funny thing is this created at date is months before we even ordered the servers for this cluster 🙃