> Microsoft Defender is detecting the latest version of Tor Browser as malware because it is using a new heuristic detection method that is designed to identify Trojans that use Tor to hide their activity. However, the heuristic method is too broad and also flags the Tor Browser itself as malware.
TLDR: Microsoft Defender is identifying any app trying to connect over Tor. The idea is malware sometimes uses Tor network to phone home, so detecting that would be a signal of potential malware.
Obviously a false positive for the Tor Browser itself.