Hi @laike9m,
If you use this command certbot-auto plugins do you see the plugin dns-cloudflare available in the list?.
If you have upgraded certbot-auto or it has self-upgraded then you have lost the dns-cloudflare plugin because in the upgrade certbot-auto removes the venv path and with that the plugins installed so you should install it again pip3 install certbot-dns-cloudflare.
If that is the case maybe you should add the param --no-self-upgrade to your cron job for certbot-auto renew command to avoid undesired upgrades and execute the certbot-auto command manually from time to time to check whether there is a new version and in case it upgrades, re-install the dns plugin.
Cheers,
sahsanu