According to the requirements of importing data " GeoJSON supports precision upto 6 decimal places so you might want to consider simplifying features. If the file size of the resulting GeoJSON is large >4MB, you will need to simplify the features. Please review the features simplification"
I am trying to import a file with a size of 2.5 MB. Still, I am getting an error message telling me that the file size is limited to 1.5 MB.
Can you please email the file? I will take a look quickly.