Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. crt.sh | example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
A change had accidentally enabled async order finalization in production. Some clients aren't yet compatible with that change in behavior on our side. I'm sorry about the trouble! We've now reverted the change, so things should be back to normal. We'll keep you updated on what we learn at our post-incident review.
Please update your Plesk and/or the Let's Encrypt extension to version 2.3.9 or newer to be future-proof with regard to asynchronous order finalization.