Not really. You happen to use a shared domain name ending in synology.me. But, you can use custom names with Synology and they have a large number of root domains that could be used (see below).
We see problems with Synology NAS more often than any other vendor NAS. And, it isn't always the same underlying failure. A laundry list of actions should be provided by Synology. Let's Encrypt can't possibly know the best actions for each Synology product and software version. Sadly, Synology main documentation is so poor we reuse a stock answer when someone was obviously mis-lead by it. If they had a good list we would have linked to it immediately.
Frankly, I think your complaints are misdirected. The email got you here which got you prompt answers from very experienced people for free. The email you showed was sent almost 2 months ago.
And, to top it off, all year you had valid certs without any gaps in expiration. The only failure is Synology (or you) not following Let's Encrypt guidelines to renew with 30 days before expiration.
From the Public Suffix List which can change at any time:
// Synology, Inc. : https://www.synology.com/
// Submitted by Rony Weng <(redacted)@synology.com>
dscloud.biz
direct.quickconnect.cn
dsmynas.com
familyds.com
diskstation.me
dscloud.me
i234.me
myds.me
synology.me
dscloud.mobi
dsmynas.net
familyds.net
dsmynas.org
familyds.org
vpnplus.to
direct.quickconnect.to