After some persistent complaints that Ishar's random number generator was
"obviously biased", the gods went a little overboard on its replacement.

When the game boots, its random number generator is seeded with a large
amount of cryptographically unguessable random data good for 10^6001 (a 1
with 6001 zeros after it) rolls without repeating.  It also corrects for the
slight amount of bias (1 in 10 million) present in the most commonly used
random number generators as they convert from binary.  The result is that if
the game asks for a 1d20 roll, the odds of producing each number are exactly
1/20, with no correlation to past or future rolls.

The problem wasn't really that the old random number generator was broken,
but that humans get confused when they see something resembling a pattern in
randomness.  If you pull a coin out of your pocket and flip it enough times,
you will eventually run into a streak of 8 heads in a row.  That doesn't make
this unusual or change the odds of the 9th coming up heads, but people
generally believe otherwise.

If you died because out of the blue you failed a bunch of rolls in a row in
a way that you consider "impossible", be assured that this isn't a bug in
anything but your expectations about how randomness should work.