Thank you for the feedback. I know that the lxc is using the time from the host machine.
I changed this settings in /etc/pihole/pihole.toml and the error is gone. If someone have the same error.
[ntp.ipv4]
# Should FTL act as network time protocol (NTP) server (IPv4)?
active = false
[ntp.ipv6]
# Should FTL act as network time protocol (NTP) server (IPv6)?
active = false
[ntp.sync]
# Should FTL try to synchronize the system time with an upstream NTP server?
active = false