Hello guys and girls can someone please help me and explain this transaction just says opt in, no tokens changed hands, it happened after a withdrawal from a cex then I received a v sample amount I have posted the transactions in order

First transaction Received from cex

Second Opt in

https://explorer.solana.com/tx/zaWoGRYd59EKK6ivSbbTF2KdjeoDAgzgLTCd9bD7j58qPbv2Edzb1cE2Fw5v42goutTRFDBAX Third Opt in

https://explorer.solana.com/tx/qZxychXysJvjsZUxJthiFMtf2d14K7KBTLiGceu2PN3k28er5d64pnWVTvpGCBeB6PwrzH1LWEAFGvtoeEbf8ML

Forth 0.000777

https://explorer.solana.com/tx/62D3sHy9Mgo5RJVVFqrxXTNgwaXnusRcWyohsyuYTGejtX7B4JUT7eH4Ue4L4dYpJoZ4pupjvxmxPraFMs4TaHH5

It all very strange as this is not my hot wallet I just use it to store sol

Thanks for any help