In UNLOCKTOOL 2022.03.21.0 - Select menu "Spreadtrum". Then, in the lower left part of the program UNLOCKTOOL , select the Brand - ZTE and device model. Next, just below, click the Erase FRP button. Previously, you must have the Spreadtrum drivers installed (before installing, disable the mandatory signature of Windows 10 drivers).
ERASE FRP Selected Model : ZTE Blade A5 2019
Code Name : P963F30
Operation : Erase FRP [1]
Authenticating... OK
Retrieving data... OK [287,15 KiB]
Hold VOL DOWN then plug-in USB cable!
Waiting for device... COM12
Protocol : SPRD3
Sending FDL1... OK [50,71 KiB]
Boot ver: Spreadtrum Boot Block version 1.1
Sending FDL2... OK [513,1 KiB]
Reading DEVINFO... OK
Model Name : ZTE Blade A51 Lite RU
Product Name : RU_P963F50_A
Manufacturer : ZTE
Platform : s9863a1h10_go_32b
Android Version : 11
Security Patch : 2021-04-05
Display ID : GEN_RU_A51LiteRU_RV1.0
Erasing FRP... OK
UNLOCKTOOL 2022.03.21.0
Elapsed time : 12 seconds
ERASE FRP Selected Model : ZTE Blade A5 2019
Code Name : P963F30
Operation : Erase FRP [1]
Authenticating... OK
Retrieving data... OK [287,15 KiB]
Hold VOL DOWN then plug-in USB cable!
Waiting for device... COM12
Protocol : SPRD3
Sending FDL1... OK [50,71 KiB]
Boot ver: Spreadtrum Boot Block version 1.1
Sending FDL2... OK [513,1 KiB]
Reading DEVINFO... OK
Model Name : ZTE Blade A51 Lite RU
Product Name : RU_P963F50_A
Manufacturer : ZTE
Platform : s9863a1h10_go_32b
Android Version : 11
Security Patch : 2021-04-05
Display ID : GEN_RU_A51LiteRU_RV1.0
Erasing FRP... OK
UNLOCKTOOL 2022.03.21.0
Elapsed time : 12 seconds