Always Free A1.Flex instance disabled after A1 limit change (4 OCPU/24GB → 2 OCPU/12GB)

Hi,
My Always Free A1.Flex compute instance in uk-cardiff-1 has been disabled and won’t accept start actions:
“Unable to start instance: Instance ocid1.instance.oc1.uk-cardiff-1.******** is disabled and will not accept any action requests. Please contact customer support to reenable.”
The instance was originally provisioned at 4 OCPU / 24GB, under the Always Free A1 limits at the time. I understand this has since been reduced to 2 OCPU / 12GB. No email or in-console notice was received before the instance was stopped and disabled.
Region: uk-cardiff-1
Instance OCID: ocid1.instance.oc1.uk-cardiff-1.********
This instance hosts live web infrastructure, so I’d appreciate a prompt turnaround if possible.