shellext.dll virus/malware?

That all looks OK, the digital signature verifies. I wouldn't be concerned about the certificate being out of date; it's exactly the same on a fresh Windows 10 21H2 installation.

Right click on the file and select Properties > Digital Signatures

Double click on the listing in the Signature List

If that says the digital signature is OK, then Autoruns is misfiring.

Unfortuantely, Autoruns development since the change to the v14 builds, has been rather buggy.

this is what is says

So I ran the Malwarebytes and even TDSSkiller yet nothing was detected. However, when I did the system scan, it said it found corrupt files and repaired them, which removed those files in autoruns. But once again, upon reboot, they come back up again. Edit: Just ran a powershell scan, it said nothing was detected, then when I hit refresh on autoruns, it disappears. So at this point I'm really not sure whats up. Edit #2: Im not sure if that has to do with anything, but when I delete the red files, and flick power switch on the back of my pc, when I turn my pc back on the files dont appear. They only appear if I press restart in windows.

Hi, that entry is normal though it shouldn't be unverified.

I suggest you scan with Malwarebytes.

https://www.malwarebytes.com/mwb-download

Set Malwarebytes to scan for rootkits as shown in the link below:

https://www.malwarebytes.com/solutions/rootkit-scanner#:~:text=Click%20the%20Gear%20icon%20and,Malwarebytes%20quickly%20scans%20your%20device. 

Then to check the integrity of system files, from an administrator Command Prompt or Powershell, run:

sfc /scannow

Let me know how things go.