clarification on huawei hisilicon phones

if possible I wanted a clarification on the fact that now almost all huawei mobile phones have a security patch that does not allow to repair imei.
I wanted to know if it is possible for these phones to downgrade the security patch and if anything, how to proceed especially for huawei hisilicon phones.
if anyone on the sigma team can clarify my ideas, I would be very grateful.
thanks and good job