Liquidity is a changing position
Depositing a token pair gives you a share of a pool. The value and token mix of that share can change as people trade.
Two tokens, one shared balance
Mooniswap pools hold a pair of tokens. Providers deposit both and receive pool shares that represent their portion of the reserves. Swaps change those reserves, so a withdrawal returns the current mix of tokens rather than the exact amounts originally deposited.
Fees follow activity
Trading fees accrue to a pool as swaps occur. A provider’s share of the pool participates in that value, but fee income depends on actual volume and the pool’s settings.
Prices keep moving
When the market price of one token moves relative to the other, your pool position can be worth less than simply holding the tokens. Virtual balances cannot remove this risk, and smart contracts carry their own risks.