It seems likely that the MIUI 12 update for Redmi Note 9 smartphone users in Europe has been temporarily halted. A new MIUI 11 stable update has started rolling out for the Redmi Note 9 instead, which will bring the device up to date in terms of security patches. Owners of the phone in China have already started receiving MIUI 12.
https://www.notebookcheck.net/MIUI-12-update-for-Redmi-Note-9-users-in-Europe-apparently-on-hold-as-new-MIUI-11-stable-update-rolls-out.479566.0.html