Grafana 10.4.3 uses keeps using alertmanager v1

Hello,
I recently upgraded Grafana to 10.4.3 and prometheus alertmanager to 0.27.0. Noticed that Alertmanger is still receiving API calls to /v1/alerts endpoint from Grafana. This Grafana version should use API v2. How to force grafana to use v2 instead of v1?

Not all alerting is migrated from legacy, could this be a cause?

these are the logs i’m receiving from grafana:

{"alertmanager":"prom-alertmanager","error":"webhook response status 410 Gone","level":"error","logger":"alerting.notifier.prometheus-alertmanager","msg":"Failed to send alertmanager","t":"2024-06-16T00:28:33.278818933+02:00","url":"https://myalertmanager.url"}