Helm events are not sent when using Telegram provider

[L3o-pold]

{"level":"info","ts":"2021-09-22T12:19:25.795Z","logger":"event-server","msg":"Dispatching event: Helm upgrade succeeded","reconciler kind":"HelmRelease","name":"ingress-nginx","namespace":"flux-system"}
{"level":"error","ts":"2021-09-22T12:19:25.816Z","logger":"event-server","msg":"failed to send notification","reconciler kind":"HelmRelease","name":"ingress-nginx","namespace":"flux-system","error":"failed to send notification to \"-*****\", response status code 400 Bad Request"}