apt update command giving error message something like this;

Err:8 https://nginx.org/packages/mainline/debian bookworm InRelease The following signatures were invalid: EXPKEYSIG ABF5BD827BD9BF62 nginx signing key <[email protected]>

Fix is simple;

sudo curl -s https://nginx.org/keys/nginx_signing.key | gpg --dearmor > /usr/share/keyrings/nginx-keyring.gpg

And then just do apt update as usual.