This is a dumb question but are telemetry intervals that far apart ? No data was sent in the last 2.1 KMs ? Or something at that level caused systems to fail immediately. Space is hard.
Spacecraft definitely do not move "very, very fast" in the terminal stages of landing, especially not on a low gravity object like the Moon. Apollo 11, for instance, spent several minutes below 2.1km altitude prior to touchdown. Soft landings on the Moon are slow events, and given that telemetry is essentially continuous, something must have gone wrong at around 2.1km.
Although the something going wrong could be as innocuous as losing antenna alignment, which happens often during landings even when nothing is really wrong, because the spacecraft is changing pitch to effect the landing.
So my best guess would be loss of telemetry due to loss of antenna alignment, followed by a bad trajectory for some reason, followed by unintentional lithobraking.
Per Twitter, it seems like something went wrong during the braking burn. The spacecraft was left tumbling (which certainly wouldn't help antenna alignment), and was thus unable to effect its landing burn.
No idea yet exactly what caused the tumbling; there's a variety of potential causes.
