Sequencer evaluates from the root sequence, so when you scrub in and out of the playback range of the subsequence, it will evaluate the other subsequences. If those subsequences have camera cut tracks, those will evaluate. Instead, you could try to turn on Keep Playhead in Playback Range While Scrubbing to prevent the playhead from going outside of the playback range accidentally.
For bugs, you can report them here: https://issues.unrealengine.com.