I know that in a In PaaS:shared-webserver service a user could have the OS of its server environment release_upgraded in 8 or 12 years or so ! For example, I host a few sites on a particular host that uses a very old version of CentOS (from about 2007).
I never used a PaaS:VPS service (like AWS/MSA/GCP) and I wonder if they have a different standard of doing OS release_upgrades; for example, I wonder if due to utilization of OS deployment tools like Vagrant, it might it be say per each new release (say, each 2 years) instead?
How frequently do PaaS:VPS agencies upgrade OS_release in comparison to PaaS:shared-webserver?
In a VPS *you* are responsible of the OS updates. AFAIK, when it is PaaS, the client doesn't control it; for example, I host a few siites on a PaaS:shared-webserver (SiteGround) and I don't control the OS --- it might be release_upgraded without me knowing this. Are you sure it's not the case for neither PaaS;VPS like AWS/MSA/GCP?... A vps by definition gives you an OS with full control. As does a IaaS, as soon as yo have admin account on the machine you have to handle the updates. Some providers gives helpers but it's still your task to configure that But were does the line line between these helpers to the OS-itself configuration gets drawn? In a PaaS;VPS of SiteGround (they also have a VPS for 60$) they told me everything stays the same; you still have SSH, cronjobs from Cpanel, daily backups and applications but AFAIK no root and no controlling of the OS... Some small answer from your experience with other PaaS;VPSs you have tried could be very helpful to understand were that line is usually drawn.