How do we know for sure that it was JL-2 instead of a few other candidates?
*JL here refers to the SL-ICBMs (i.e., JuLang) instead of the AL-ICBMs (i.e., JingLei).
Because:
JL-1 - Would have been retired by now, alongside its sole carrier (i.e., the 092 SSBN). The missile also couldn't reach beyond 2000 kilometers. Hence, what for?
JL-3 - This is the latest SL-ICBM in active service with the PLAN. Hence, it is doubtful that they would unveil their latest strategic missile in a full-range test at this time (going by the same reasoning for the full-range test of the DF-31AG instead of the newer DF-41 conducted by the PLARF back in September 2024).
JL-4 - Not a thing yet, as this SL-ICBM is meant for the 096 SSBN. Besides, it's pretty doubtful for this under-development missile to conduct a full-range test, where things could go wrong (and can lead to accidental dropping of missile debris over unintended areas).
In addition, in the case of JL-3 and JL-4, where both SL-ICBMs are expected to have strike ranges above 10000 kilometers - Conducting a full-range test towards the South Pacific with a range of only about 7000 kilometers certainly seems weird.
On the other hand, there is no known submarine-launched ballistic (or even hypersonic) missile in the PLAN arsenal besides the JL-series with a strike range of 7000 kilometers.
So that leaves the JL-2 as the most probable missile deployed in this test.