How to make persistent modifications to /etc/zshrc

Every time macos is updated, the /etc/zshrc file is overwritten. The /etc/zshenv file was untouched before BigSur. However, both of these files are now being overwritten on every update. This have been an issue for setting up reliable nix environment on macos.

All I need to do is set a few environment variables (PATH, NIX_PATH, NIX_PROFILES & NIX_SSL_CERT_FILE) system wide.

Can someone please provide a solution for this?
How to make persistent modifications to /etc/zshrc
 
 
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