After initially being merged in #20487, it’s no-longer clear that an internal syscall sandboxing mechanism is something that Bitcoin Core should have/maintain, especially when compared to better maintained/supported alterantives, i.e firejail.
There is more related discussion in #24771.
Note that given where it’s used, the sandbox also gets dragged into the kernel.
If it’s removed, this should not require any sort of deprecation, as this was only ever an opt-in, experimental feature.
Closes #24771.