Renewing Expired Let's Encrypt Certificates

I’m using a mattermost docker installation. My certificate expired for the second time - once after 90 days, and today, after 180 days. I did the standard renewal. The output says the certificate has been renewed. But sslchecker says it is not. And I still get an untrusted certificate error. What am I doing wrong? Please help.

My domain is: matter.takshashila.org.in

I ran this command:
./scripts/issue-certificate.sh -d matter.takshashila.org.in -o /root/docker/certs

It produced this output:

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Renewing an existing certificate for matter.takshashila.org.in

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/matter.takshashila.org.in-0001/fullchain.pem
Key is saved at: /etc/letsencrypt/live/matter.takshashila.org.in-0001/privkey.pem
This certificate expires on 2023-01-24.
These files will be updated when the certificate renews.

NEXT STEPS:

* The certificate will need to be renewed before it expires. Certbot can automatically renew the certificate in the background, but you may need to take steps to enable that functionality. See [User Guide — Certbot 1.31.0 documentation](https://certbot.org/renewal-setup) for instructions.

This was the result of “certbot certificates”

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Renewal configuration file /etc/letsencrypt/renewal/matter.takshashila.org.in.conf produced an unexpected error: renewal config file {} is missing a required file reference. Skipping.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The following renewal configurations were invalid:
  /etc/letsencrypt/renewal/matter.takshashila.org.in.conf
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Can some kind soul please help me?