What is the problem with the server?

Question

MySQL

Good afternoon.
There was an interesting situation, it would be desirable to hear opinion of skilled system administrators.
There is a VPS server on CentOS 7. It has been serviced by one provider for about two years. A couple of days ago (wording from a technical support letter) "an incident was recorded that caused hardware failures. As a result, this affected the availability of the virtual server." In other words, the server crashed and didn't work for 12 hours. After my appeal, it was restored from a backup made by the provider the day before. I was given "bonuses" as compensation. And everything seemed to be fine.
But!
After restoration the server works with one serious problem. After each reboot of the MySQL server, it works for 5-15 minutes, then it crashes. Accordingly, all sites stop working. I note that before the "incident" such situations never happened (the server could work for 200 days without a reboot, after reboots everything also worked well). I also note that after the restoration, no "movements" on my part were made on the server. All settings are the same as they were before the "incident".
As far as I was able to google, the reason may lie in the lack of memory (I'm not good at reading logs, etc., so I can't say for sure - maybe you can help).
My question is this: purely theoretically / technically, with all of the above, how likely is it that the problem is on my part (server settings, unoptimized website code, etc.)? Could it be that after restoring the VPS, the server was deployed on another hardware - a weaker one, for example? Or some other cant provider? Or is it my fault anyway?

I repeat: no settings of the server and sites were changed shortly before and after the "incident". The problem is observed from the first minute of server operation after recovery.