Just want to add something in here, as there seems to be a little confusion.
Erasing the EFS (modemst1/2) is a standard part of the OTA process and the fastboot process if you use the same commands that are in the relevant XML file that comes with the fastboot zips. this is also what lenovo smart assistant will do.
The EFS is recreated each boot if it doesn't exist. The only time that it doesn't get recreated is if there is an unrecoverable problem with your persist, specifically the key file dhob.bin.
So, to be absolutely safe, use the backup option in the TWRP flashable builds, and save the backups into the cloud. Of course, there is no guarantee that you don't already have an issue with your persist, in which case the backups of your EFS backups should be safeguarded with the greatest of care.
refer to this thread for more information
https://forum.xda-developers.com/g5-plus/how-to/fix-persist-resolve-imei0-explanation-t3825147 t