Excel Auto Date conversion - Changing 1939 to 2049 etc

I urgently need some support in Excel 365 (Power Query) and Microsoft need to fix this issue.

For example

I download data from a database containing date of births. These all display correctly in the system.

When uploading them into a CSV, for some reason a large amount of dates automatically convert to 2039 and 2049

I have tried everything to fix this and have run out of patience.

[ATTACH]790270

To be honest this should display the data how it was exported, why would you need to see future dates here.

This functionality urgently needs to be fixed as it wasting a lot of peoples time.

I could make a list of issues with Office 365 and Power Query, but this is a critical element.