How could I find out if that address is a blockchain.com address?
The only way to be sure, is to find that address in your account. But it looks like you already found it there.
I logged in to blockchain.com in 2024 and I saw my Bitcoin address with the Bitcoin amount, but I couldn't use it because it wasn't in a wallet.
I needed validate my blockchain.com account, after I did that, I got a new wallet (probably a DeFi wallet?) and I didn't see the address anymore.
That blockchain.info/.com webwallet is an endless source of problems. This is what I have collected on them:
- Blockchain.info: To recover an old legacy Blockchain.info wallet, read this topic and go here.
- Blockchain.info: In some cases, Blockchain.info (now .com) shows a compressed private key while the address was uncompressed. Read this topic.
My guess is it could have to do with the last option in this list.