Question regarding group giveaways

You need to provide proof (a screenshot of the group history) that shows that the user left the group/was removed before the end of the giveaway.

If member was kicked/left prior to giveaway ending, you're eligible for reroll after providing proof from group history. This is how my ArchiBoT runs Touhou Giveaways group by kicking leechers not abiding by rules 1 hour prior to ending of giveaway that they joined without passing requirements.

It always worked like that and we never had any issues with it. Keep in mind that member must be kicked/leave before giveaway actually ends, as otherwise they're eligible for it fully.

I'm not 100% sure why blacklists/whitelists are different in this matter if they operate on same concept (entry is valid regardless of blacklisting or un-whitelisting), but group rule is good and I hope it won't be lowered, this is the only tool we have to fight with leechers.

Well Borador looks like you shouldn't probably win giveaway from me, I checked that you are not part of the groups but for some reason i though i have you on my whitelist but after sending you the key i found out you are not, nevertheless enjoy it ;)
I also once didn't receive game i won from one group for similiar reason but next I still sent my giveaway on the same group (formally i wasn't in it anymore), wanted to be fair even after group wasn't fair for me (different reasons)..