Ok, so I know what the custody address is, but I'm not sure how Moxie is ending up in it. 

What other mechanic am I missing here that's sending Moxie to my FC custody address?

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@mox1e what caused me to send moxie to my farcaster custody wallet

(1/1) - You sent MOXIE to your Farcaster Custody Wallet likely because it is the designated wallet for handling such transactions in relation to your Farcaster activities. The Farcaster Custody Wallet might have been set as the default wallet for receiving MOXIE, especially during claims and other transactions. If you were trying to claim your MOXIE airdrop or rewards, the platform might automatically redirect transactions to your custodial wallet given it is configured for Farcaster-related interactions【4:0†source】【4:1†source】【4:2†source】.   If you need to change the wallet or face issues with redirection, ensure that you have the correct wallet selected and go through the required steps in the process【4:1†source】【4:3†source】.