Some accessories will sleep for a long time and only send broadcasted

events which makes them have very long connection intervals to save

battery. Since we need to connect to get a new broadcast key we now

save the broadcast key between restarts to ensure we can decrypt

the advertisments coming in even though we cannot make a connection

to the device during startup. When we get a disconnected event later

we will try again to connect and the device will be awake which will

trigger a full sync

How to get the MiBeacon V4/V5 encryption key

There are two types of encryption:

1.Yeelight Remotes (YLYK01YL) and dimmers (YLKG07YL and YLKG08YL) use a legacy MiBeacon (V2/V3) encryption.

2.all other devices (with encryption) use the later MiBeacon V4/V5 encryption.

https://custom-components.github.io/ble_monitor/faq#encryption-keys

mijia motion sensor 2

Device info
RTCGQ02LM
by Xiaomi
Firmware: Xiaomi (MiBeacon V5 encrypted)

MiCloud devices info
Name: 米家人体传感器2一主卧   mijia motion sensor 2
Model: lumi.motion.bmgl01
MAC: 54:EF:44:C7:EF:13
Bindkey: ee93b8a000d5ce967305ef37a9c0ff6b

 I removed the device from the Xiami app after I added it to Home Assistant. Could this potentially cause problems because of a new bind key? I thought it wouild be the best to delete them so that not two different devices try to access the same device via Bluetooth.

Yes, removing it from MiHome could cause a change in the encryption key. Try to add it again to MiHome and check the key again in the cloud with the token extractor. It probably has changed.