We don't really know the true reason why most Bounty managers back then are no longer managing bounties now. But for me, the most likely main reason is the decline in participation of investors in ICOs, token sale nowadays, unlike during the 2017 bull run when they were actively investing. So, because of this reason, there are now fewer projects offering bounties.
After several years looking for good bounty. I think the era is now ended, there are not much good bounty nowday
So this forum is replaced as the main source to get more community the crypto is moving towards social media like Twitter to gain more popularity from that there will be less and less airdrop and bounty from the crypto project that listed in here.
This is just my opinion.
I think so, most common project in the bounty seem like fail to get more attention in this forum