Decimal mark unclear

An uploaded file separates its fields with semicolons, and its numbers do not show whether a comma marks decimals or thousands: 1,234 could be either. The numbers were kept as text rather than read one way.

What to do

Save the file again with a point as the decimal mark, or upload the spreadsheet itself as .xlsx.

Where it comes from

Shown by Import Data. It is one of the messages about a node.