The number of bingo tickets sold is increasing as more players join.
We originally started with 38,600 SP, and we’ve now increased it to over 460,000 SP. That’s one of the reasons we had to recalculate and adjust the upvote to 75% for 5 tickets.

Voting mana plays a big role when giving upvotes. Our mana has been gradually decreasing every day, and if we had continued giving 100% upvotes for 5 tickets, the value of those upvotes would have dropped significantly.

With the new setup, mana will build up again each day, meaning upvotes will be worth more in dollar value.
The calculations shown above are based on a voting power of 60% mana. As that mana increases, so will the value of the upvotes players receive on their posts.

Until now, all upvotes have been given manually. Soon, the process will be automated — this will help preserve mana because votes will be spaced more efficiently, avoiding bulk voting in a short time, which causes a drop in mana.

I’ve also checked and confirmed: you were right — you should have received 75% upvotes from all accounts in the trail. I apologize for the oversight.

With the increased SP and higher mana levels, you can expect to receive around 8–10 STEEM back, which means you're still getting a good return for the 5 STEEM spent on bingo tickets.