The assessed value represents the estimation of market value of the property. The real estate market changes frequently.
Example, your assessment for Fiscal Year 2023 represents the market sales in the calendar year of 2021.
So, though no improvements or physical changes have been made to the property, the buyers are willing to pay more for your type of property. Which then causes a seller's market and increases the sale prices of homes. The assessment follows what the real estate market is doing.