Dear user.
Thanks for reaching out to MIUI ROM subforum.
Redmi 9T is not under current MIUI 12.5 Stable ROM eligible device list. However, this doesn't mean Redmi 9T will not get MIUI 12.5 since Xiaomi will announce more eligible devices in the future. You may stay tuned on Xiaomi Official Social Media accounts, MIUI Official Website(en.miui.com/v12_5) and Mi Community for any news regarding this.
Thanks.