Already have disabled it in the previous rom update...What is using "more" your battery on 20.1.2?
What you can do => Disable "Email" app if you don't use it or downgrade it => https://xiaomi.eu/community/threads/emaill-app-sync-issues-version-20191206.54102/
I have a Mi 9T too and I don't see a signifiant change for the battery yet...
EDIT: And you can try to wipe Dalvik&Cache in TWRP first, it will not hurt.
And continues disabled now...but thanks
Will try to wipe dalvik cache again....normally I do after install a update and before a reboot