Xiaomi has now halted MIUI 12 development for the Redmi Note 7 and Redmi Note 8, for two different reasons. The company also suspended the MIUI 12 rollout for the Mi 10 and Mi 10 Pro—due to optimization concerns.
https://www.notebookcheck.net/MIUI-12-development-halted-for-the-Redmi-Note-8-and-Redmi-Note-7-ahead-of-Android-10-release.476823.0.html