[exim] Database lookup tainted

Hi,

I currently have a setup where alias mail addresses are looked up from a postgresql database
(multiple delivery targets possible)
This works fine in exim-4.93

However after updating to 4.94 I only get errors like this (private details replaced):

2:19:39.350 12159 ╭considering: ${lookup pgsql {servers=127.0.0.1/mydb/mydbuser/mydbpw; SELECT
string_agg(DISTINCT userid,',') AS target FROM aliases WHERE
address='${quote_pgsql:$local_part@$domain}';}}
12:19:39.351 12159 ╭considering: servers=127.0.0.1/mydb/mydbuser/mydbpw; SELECT string_agg(DISTINCT
userid,',') AS target FROM aliases WHERE address='${quote_pgsql:$local_part@$domain}';}}
12:19:39.351 12159 ╭considering: $local_part@$domain}';}}
12:19:39.351 12159 ├──expanding: $local_part@$domain
12:19:39.351 12159 ╰─────result: myuser@???
12:19:39.351 12159 ╰──(tainted)

What do I have to change to make this work again?
What is the reason it says tainted?

Thanks,
Daniel