This error typically indicates that the function has timed out. If our functions in Google Sheets take more than 30 seconds to execute, you will receive the error message: “Exceeded maximum execution time”.

This is a limitation imposed by Google itself. Quotas for Google Services  |  Apps Script  |  Google for Developers

This issue usually resolves itself and rarely becomes a significant problem. A workaround for this is to delete the formula and then undo it.