If want connect App " xiaomi earbuds " , it need change the App region to china ,

it will work ok.

Product type：Semi-in-ear true wireless Bluetooth earbuds
Earbuds: M2540E1; Charging case: EC2501
Frequency response range：16Hz–40kHz
Dimensions and weight
Weight of a single earbud：4.4g (±0.2g)
Dimensions of a single earbud：31.77 x 17.17 x 20.56mm
Weight of charging case：34.5g (±1g)
Dimensions of charging case：52.34 x 52.57 x 24mm
Total weight：43.4g (±1g)
Charging
Battery capacity
Earbuds: 35mAh; Charging case: 475mAh
Charging port：Type-C
Earbud input parameters：5V⎓100mA
Charging case input parameters：5V⎓700mA
Charging case output parameters：5V⎓200mA
Battery life
Battery life of a single earbud (ANC off)：6 hours
Battery life with charging case (ANC off)：35 hours
Battery life of a single earbud (ANC on)：3.5 hours
Battery life with charging case (ANC on)：20 hours
*Battery life refers to music playback time. Test conditions: Bluetooth codec set to AAC, volume at 50%, with all other settings in their default state.
Battery life of a single earbud (ANC off)：5 hours
Battery life with charging case (ANC off)：28 hours
Battery life of a single earbud (ANC on)：3 hours
Battery life with charging case (ANC on)：19 hours

*Battery life refers to music playback time. Test conditions: Bluetooth codec set to aptX Adaptive, volume at 50%, with all other settings in their default state.

Wireless connection：Bluetooth
Bluetooth protocols：Bluetooth® Low Energy / HFP / A2DP / AVRCP
Bluetooth version：BT5.4
Bluetooth codec：AAC / SBC / aptX Lossless / aptX Adaptive / LC3 (only on selected models)
Operating distance：10m (open space free of obstacles)
IP rating：IP54 (earbuds)
Package Contents：
Xiaomi Buds 6 x1
Charging case x1
Type-C charging cable x1

User manual x1