I believe it is possible to unseal the volume and disable these protections, a quick google seems to indicate this. Apple usually does seem to provide (a maybe annoying) way to bypass these sort security measures.
He described how he does exactly this - and has to reapply it after every update.
I'm still on Catalina. I've read reports that on Big Sur you cannot remove the kext and re-enable CSR. Seems the only solution might be to leave csr disabled, which would be unfortunate.
I don’t believe you can turn on file vault if you do this (full disk encryption)