The other thing of note for SVE is that, with the default function ABI all of the SVE state is call-clobbered, which allows the kernel to drop instead of save state across system calls. (There is a separate vector function call ABI when SVE types are used.)
For the RV psABI, it is similar - all V regs are caller-saved/call-clobbered [1] and syscalls are not required to preserve V regs [2]
However last I checked ARM documentation the ABI doc seemed to suggest that some (parts) of the SVE regs are callee-saved [3]
So while strcpy may enable SVE for the thread, the next syscall may disable it again.
Next syscall could trash them, but will it disable SVE ?