Until randomSeed() is invoked for the 1st time there’s no seed yet, so random() merely invokes JS builtin Math.random() till then:
The local constant randomStateProp contains the string name of the “secret” seed property:
And that property is initialized w/ null by default:
We can log that property like this: print(_lcg_random_state);
AFAIK that “seed” algorithm is used by both Java Mode & Pjs flavors as well.