An online casino got hit a similar way a long time ago, iirc someone realised the seed for a known prng was the system clock, so you could brute force every shuffle either side of the approx time stamp and compare the results to some known cards (I.e. the ones you’d been dealt) once you had a match you knew what everyone else had.

Always thought that was elegant (the attach not using the time as the seed).

Can you not just add salt to seed and make it true random? seems like under engineered solution to me.