Many people are in doubt about the fairness of the lottery.
... if someone can figure out a way to implement a provably fair lottery with a variable number of tickets given out each round, I would be happy to implement it. So far I haven't been able to figure out how to do it myself.
Maybe you should use some third-party intermediary for generating random user IDs for the lottery? For example, there is "Audited Lotteries and Sweepstakes" option in random.org.
https://www.random.org/guides/draws/