Seed phrase
A seed phrase is a series of words that records access to a wallet. With those words a wallet can be set up again on another device. Whoever holds the seed phrase effectively holds the access, which is why the series is kept carefully.
What it may indicate
Losing or sharing a seed phrase can have major consequences, but it does not automatically mean something is wrong. Sometimes it is carelessness, in other cases deception. What actually happened only emerges from investigating the transactions that followed.
What is a seed phrase?
A series of words with which access to a wallet can be restored. Whoever has the series effectively has access to the wallet.
What happens if a seed phrase is shared?
Sharing it can give someone else access, which may lead to funds being moved. Whether misuse occurred only emerges from investigating the transactions that followed.