This occurs when your price range is not balanced 50/50 around the market price. In many cases, it is not possible to balance exactly 50/50 due to the logarithmic spacing between price ticks. Generally if the ratio is close to 50/50, there is no reason to worry.
Under the hood, the Uniswap v3 protocol divides prices up into discrete intervals known as ‘ticks’. These ticks use logarithmic space. The size of the tick is a function of the fee tier — generally, the tick is double the size of the fee tier (e.g. a tick for a 0.30% fee tier pool will be 0.60% in size and there will be a tick every price 1.006^n where n is an integer and price is the relative price between token0 and token1).
In order to deposit at 50/50 values, a user has to find two ticks that are equi-distant (in log space) from the current price: as an example, if the current price of an asset is 1,000, a 50/50 deposit with a +/- 10% range would require prices at 900 and 1,100. However, there may not be ticks at exactly 900 and 1,100, which produces an even deposit value.