You might be correct. If the placement_startdate column in your Azure Data Factory data flow is already in a date format, you might not need to use toDate for your comparison. The toDate function typically converts a string or a numeric type to a date type. If placement_startdate is already a date, this conversion would be redundant and could potentially cause issues.
Instead, try using the condition directly like this:
placement_startdate >= '2023-08-01'