Failed to expand return path when forwarding emails

I recently set email forwarding for a few of the email accounts and in paniclog there are errors:

2024-06-10 13:14:02 1sGKyc-002iFr-Js == <> R=dnslookup T=remote_forwarded_smtp defer (-1): Failed to expand return path “${srs_encode {${readfile{/etc/exim4/srs.conf}}} {$return_path} {$original_domain}}”: empty address

Ubuntu 22.04

What is the content of:
/etc/exim4/srs.conf

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