Actually, it has been discussed in length here on the forum since the beginning of 2021. Also, Plesk always has up-to-date software requirements published on
Software Requirements for Plesk Obsidian.
In addition to that, several Plesk Knowledge Base articles have been published on migration procedures. But even if you missed all these, the Internet itself is full of warning advices on the EOL of CentOS 8. Even a simple Google search for "CentOS 8" brings up an article in the first result rank that in its excerpt states: "Feb 9, 2022 — The
CentOS Linux
8 packages have been removed from the mirrors."
It's really not something that other software vendors must tell customers, but a very typical system administrator job to maintain a system properly. Besides, Plesk had extended availability of their archives beyond the end of CentOS 8 for months at the beginning of 2022. Is it really thinkable that after all the news online on EOL of CentOS 8 a responsible system administrator could not know about it and even after December 31st, 2021 has passed, this was still not noticed?
Plesk delivers a wealth of tools and information, but in the end, we cannot operate your server for you. The basic operating system tasks are the responsibility of the system administrator. Even now, that all this is long past, Plesk still gives you options how to migrate your existing installation. I do understand that this is a lot of work for you now, but it is the maximum that a software vendor can do.
If you do not wish to do the migration process yourself, Plesk might even be able to help you beyond what is our responsibility. For that case I suggest to contact Plesk Professional Service if they can migrate your system for you at cost. Please check it out here:
Professional Services Free Plesk migration assistancePlesk offers free migration assistance from older Plesk versions and other panels in the supported panels list. The option is available for Plesk commercial license owners and covers the installation of migration tools, environment...
www.plesk.com
I do not want to sell you something, only trying to ease the situation for you. But please also understand that beyond the enormous number of support steps that were already taken since the beginning of 2021 we are now in 2023 and EOL of CentOS 8 is long past. It is just not possible to maintain old systems forever.