what makes the ble transmission speed difference in different Android device?

I had a awesome trouble with the ble when update my firmware, with the same code in app and firmware, the samsung s10(android 10) and s7edge(android 8.0) can send 510+K files in about one minute, but the honor V20(android 10) and xiaomi cc9(android 10) need about five minute!! the Connection Event is already to fill the Connection Interval(11.5ms) .