text field exported in csv file, converted in date field

Using Projeqtor V7.0.5 and screenCustomization v5.1 plugin, I have craeted new text fields on the Tender object. When I export some tenders, the custom text fields are converted in date fields depending on their content : 2/4/6, or 10/20/70, or 2-4-6, or 10-20-70.
That doesn't happend with space or dot : 2 4 6 or 2.4.6, or if I add few additional characters : 2/4/6 months or 10/20/70%.

Custom fields are defined as varchar. Shoud I use another type?