USB flash shows symptoms of infection but none detected

oh! And yes, both my security tools are up-to-hour if you will.

I agree that something definitely smells bad. For one, there is an "autorun.inf" file, a file typically used to exploit a serious Windows vulnerability (the autorun "feature"). Then there is a misterious "bat.bat" file. And a couple of shortcuts pointing to who knows where, presumably taking place of the original files. To me it's clear that the pendrive at least touched an infected computer.

I wonder where do the shortcuts point to, and what the bat file and autorun actually do. But most likely there is something bad inside that trash folder, maybe a malware plus backups of your files. I would simply not take chances, just reformat the drive right away and restore whatever was there from backups. Other than satisfying curiosity I see little value in peeking around, specially considering Windows loves to run the autorun thing without consent.

BTW, don't put too much faith in antiviruses. They're completely unreliable since years ago. A bit of common sense plus a good configuration is far more useful, as you've seen detecting the malware by yourself