That's because it is a stable build. Note you don't have EU in the build name like the beta.Well i got it as an OTA update, and i don't have "receive updates early" checked.
It only says "Stable" on my phone.
That's V188.8.131.52.RJKEUXM you have linked.This is a known issue (threads on xda). Receiving the update before or signing up for the beta program may also be the cause.
I advise you to change the title of the thread to avoid that some install the rom and then post that they have problems with this rom.
Look at here https://xiaomifirmwareupdater.com/archive/miui/lmi/