tl;dr: It's probably a pair of small drones with LEDs or a satellite flare next to something unidentified.
To me this could look like a pair of small drones with LEDs. One remains static and the other slowly rotates so that it appears to brighten and dim as it passes the other.
Some have Lambertian distributions (see more in this answer) but with the plastic lenses it can be more focused and so a smaller rotation can produce the same light curve.
It looks like the object that brightens then dims through a huge range (from saturation to invisible) does so over only about 10 degrees or less. There's no way to do both like that just from Sun and Earth's shadow.
It could be a satellite flare though! See questions and answers here tagged satellite-flare for more on that.
It does look a lot like what a flare should look like. I don't think Starlink satellites have the capacity to flare this brightly, but perhaps some do.
If it's really a satellite, then it's probably a flare.