Ubuntu 22.04 shows "RETBleed: WARNING: Spectre v2 ..." message at startup

In many hosts through VirtualBox 6.1.38, for many Virtual Machines: Ubuntu Desktop/Servers was accomplished an upgrade from 20.04 to 22.04. The process was successful.

Now for all the Desktop environments (not sure if happens for servers) when Ubuntu is loading appears this message:

RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!

This message only has appeared for this 22.04 version - therefore never for previous releases such as 18.04 to 20.04

My concern is:

• Is it a direct bug about security of Ubuntu itself? - or
• Is it "something" caused by VirtualBox?

How to fix this situation?

Note I can work in peace through all these Virtual Machines.