When you set a listing's base price in Guesty, it automatically updates in Expedia. At the same time, Expedia automatically calculates your minimum and maximum rate threshold for the listing based on previous reservations and uses that range to validate any rate updates from Guesty. If the Guesty base price falls outside of that range, Expedia overrides it.
Guesty will notify you via email upon after the first time Expedia overrides your Guesty base price.
To resolve the issue, contact Expedia to change the rate threshold or update the base price in Guesty to reflect Expedia's rate.