The file was saved as UTF-8 and opened as if it were Windows-1252 (or the other way round). Pick the correct encoding in the preview until the text looks right, then download the fixed CSV.
The delimiter does not match what is expected. Select semicolon, comma or tab in the preview, check the columns and download the file with the right delimiter.
No. If characters were already replaced by question marks or unrecoverable symbols, the original information is lost and cannot be restored. Always keep a copy of the original file.
No. The repair runs in your browser and the CSV never leaves your device, which matters for customer lists or shop exports. Large files may take longer to process.