This will be better:
tapo_test_sub_r90:
- "ffmpeg:rtsp://xxx:xxx@IP:554/stream2#video=h264#rotate=90"
This one will never work. Because the codec of the first and second source is the same (H264). And if the client requests this codec, go2rtc will choose the first source with this codec.
tapo_test_sub:
- rtsp://xxx:xxx@IP:554/stream2
- "ffmpeg:tapo_test_sub#video=h264#rotate=90"