Regarding Observation 7860718 … Does this observation have incorrect/outdated TLE’s?
I don’t think so, the TLE was updated near the observations start time. If you are wondering for the signal at the top right, if the station performs well on other observations, then it may be one of the other satellites of this launch, check the array in the first post in this thread that is sorted by frequency to find out which ones could be visible in the waterfall of CUBEBEL-2 observations.