Same problem here. Core version 2023.3.4, though I have seen this happen once in a prior version. Earlier, I created a full backup and Windows Defender found the trojan. Deleted the backup, created another full backup and it’s clean. Made a full backup today and again got the alert. Tried downloading the backup again and again got the alert. Deleted said backup, created a new one but this time had the trojan detected.
Funny thing is, I have scanned my system and not found this Trojan anywhere else.
Edit: After getting a positive alert from Windows Defender, I ran a scan with Avast. Did not get any alert there so I am iines to believe this as a false positive from Windows Defender. Will update if I find something new.
Edit 2: After updating to Core 2023.3.6, I made another full backup and ran a scan with Avast - no alerts received. I then scanned this new backup with Windows Defender and again, I did not get any alert.
Here’s the weird part - I scanned the old backups (the ones which were flagged as infected by Defender) again with Windows Defender and this time I did not get any alerts. This, combined with the fact that I would frequently get an error in Windows Defender that the Threat Service has stopped leads me to believe that Windows Defender is the culprit. I’ve switched to Avast completely for now. In case I have something else to report, I’ll update here.
Hope this helps.