Is it possible to disable the Let's Encrypt certificate auto-renewal on a Plesk server?
It's not possible to disable the Let's Encrypt certificate auto-renewal for the particular domain.
To disable the Let's Encrypt certificate renewal for all domains:
Go to Tools & Settings > Scheduled Tasks.
Find the Extension letsencrypt and/or Extension sslit tasks
keep-secured.phpand click on the green dot to disable the task:
Note: this will also disable the automatic certificate renewal for the Plesk login page and mail server.