Thank you for a response. I already emailed to bad-relays@lists.torproject.org. They don't know why does this happen. They suggested to delete a /var/lib/tor/keys folder and restart Tor. It seemed to help, but a day later these error messages started to appear again. 
Have you had the same problem?

On Sun, Jun 20, 2021 at 7:10 PM <charles@torrelays.ru> wrote:
Your Tor relay is marked as a bad relay. This could be due to the fact
that your family is setup wrong, or just a mistake on Tor's end. Just
email
bad-relays@lists.torproject.org and they'll fix it for ya



On 2021-06-19 15:24, Zakwan Kalb wrote:
> Hi, I have an issue: a day after I start my relay I get a bunch of
> error messages from Tor.
> Here is an example:
> http status 400 ("Fingerprint and/or ed25519 identity is marked
> rejected -- if you think this is a mistake please set a valid email
> address in ContactInfo and send an email to
> bad-relays@lists.torproject.org mentioning your fingerprint(s)?")
> response from dirserver 204.13.164.118:80 [1]. Please correct.
>
> Did anyone have the same issue?
>
> Links:
> ------
> [1] http://204.13.164.118:80
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> tor-relays mailing list
> tor-relays@lists.torproject.org
> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
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