To fix this issue, you need to normalize the dates and handle them consistently across your React app, MongoDB, and Express API:

1. Normalize Dates to UTC When selecting a date range in your React Calendar component, ensure you strip the time component and work with UTC dates:

javascript Copy code const normalizeDate = (date) => { const utcDate = new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate())); return utcDate; }; Use this function when saving dates to MongoDB.