What a deployment train looks like
The classic pattern is many points following nearly the same track at a similar speed, with fairly regular spacing. The train can brighten, fade or disappear as the satellites enter Earth shadow. It does not need to remain visible from horizon to horizon.
What weakens Starlink
Independent blinking, changing formation, sharp turns, hovering, large differences in speed or lights moving in opposite directions weaken a satellite-train interpretation. Perspective can still create surprising apparent changes near the horizon.
Why timing matters
The most striking trains occur after launches while spacecraft are still relatively close together. Later they spread around the orbital plane and no longer resemble a neat chain. A generic Starlink-exists answer is therefore not enough.
How the checker treats it
Multiple lights plus steady shared motion produces a strong Starlink-pattern fit. The result remains a pattern classification unless an exact orbital pass has been verified from appropriate orbital elements.
Verification sources
Use NASA/JPL CNEOS, CelesTrak, ADSB.lol, NOAA SWPC and Launch Library 2 according to their coverage and time window. Sky Event Radar keeps missing evidence explicit.