Go into Settings and type "Security"
Click "Windows Security Settings" (top item) then from there clickOpen Windows Security.
Three up from the bottom on the left click Device security.
You'll get this:
Select the first one, Core isolation details if its there.
If you have a reasonably-recent processor that can do virtualization there will be an entry called "Memory Integrity" as the only entry.
Note: If it's not there then shut down, go into the BIOS and see if you have something called "VT-x" in BIOS settings (may be in an "advanced" tab) and its there and disabled turn it on. At the same time look for a "PTT" entry in there and if that is off turn it on -- that is software TPM 2.0 support which Windows 11 will allegedly require. If neither option is in your BIOS then your CPU is probably too old and unfortunately this is not available to you.
If it's off turn it on.
It may fail. If it does it will give you a clickable list of the reasons.
The reason(s) are usually old device drivers and similar.
Those may or may not be hidden time bombs that are siphoning off data; every one of them has privileges and thus can interdict anything it wants and exfiltrate it off your machine.
If you don't know what they are find out and, if possible, remove them. Getting rid of them can be a bit complex but it can be done.
Reboot.
Then get an elevated command prompt (click the windows, type "CMD", right click BEFORE you hit enter and select "Run as Administrator") and in the command window type "SFC /SCANNOW".
If there is anything found and repaired you almost-certainly had some piece of crap on your box.
You're welcome