Why are my coins disappearing from MetaMask?

Hello, I've been noticing some strange occurrences with my MetaMask wallet. I've been keeping a close eye on my coin balances, but recently I've noticed that some of my coins seem to be disappearing. I've double-checked my transactions and there's no record of me sending or trading these coins. Can you help me understand why this might be happening and what steps I can take to prevent it from happening again in the future? Thank you.