DataQualityCheck - Violation report showing different data type for a column

While doing the data Quality check between baseline and current run data, check is getting failed and getting violation report -- when we checked the violation report .json file, it shown that for 3 columns we are getting this error as "Expected data type: String, Expected match: 100.0%. Observed: Only 87.44% of data is String."

So we tried analyzing that particular 3 columns if there is any datatype mismatch and figured out that while doing the comparison on the current run data set, even though the actual data in that column is string datatype, few numbers are also present in the column but as a string datatype (for eg:"300". "500"). for testing purpose i m giving same dataset as input for baseline and the current data can someone let me know what could be the reason for this to happen.