Need help understanding this transaction (Naive Noob)

I bought some BTC for 940. Spent 40 at one location advertising site. Then I authorized a 100 spend for an advertising site that ended up ballooning into 890 spend at the close of the transaction.

Looking at the advertising site, the ledge shows that I did fund 100. But when I look at the blockchain transaction, it shows that the 890 was split into two, 100 and a 790. I looked at the time frame of transactions and it lines up perfectly.

Is a passenger transaction even possible?

Did I commit user error somewhere, like oversending? If I oversend, where does it go?

Is this the right place to ask this question?

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Bitcoin transaction log

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Ledger from advertising site

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Transaction from Coinbase Wallet