Quote from: Maverick Zeng on Today at 07:00:08 AM

I'm still a bit unclear. I used a scrambled, incorrect mnemonic phrase from that Facebook phishing scam, and it successfully imported into Electrum wallet using the [BIP-39] format option. However, when I tried to import it into other mainstream wallets using their BIP-39 format, they all failed!

Read the first sentence in my previous reply for his.
That combination is not a valid BIP39 seed so other clients wont recognize it as BIP39 seed,
Electrum as well, with that warning message, but it will still let you proceed to derive a wallet based from those words.

Quote from: Maverick Zeng on Today at 03:46:50 AM

Through an accidental misreading of the image, I incorrectly interpreted the mnemonic's order as a standard sequential 1.2.3.4.5... (horizontal) layout, rather than its intended 1.7.2.8.3.9... vertical arrangement.

Quote from: Maverick Zeng

Furthermore, the wallet address that Electrum opened after successfully importing it with the BIP-39 format option was not a newly created Electrum wallet. Instead, it was an address that someone else had been using for several years, and it even had usage records from just the past few days.

Those words are posted in public, that isn't a coincidence and not random.
It's just someone else did the same thing as you did and used that wallet or the poster is already aware of it.

A collision in when you randomly select from BIP39's wordlist and you created an existing wallet.