Yep. It goes away on Poco if you turn off auto brightness. It's the same on the official Xiaomi ROM so xiaomi need to fix it. Unfortunately when they introduce a bug that seemingly doesn't affect every user they often don't fix it for months (if at all)Since ROM 9.5.30 is it often not possible to wake up the phone from standby mode by using fingerprint sensor.
Please fix this bug, it's very annoying.
Mi 8 User