Drawing a time chart in Numbers 11
The format of your dates is not one of the date formats in the US version of Numbers, so the dates are interpreted as arbitrary text values. When you change dates to something universal like 2021-01-10 then the dates are recognized and the distance along the horizontal axis is proportional.

You may also have to select the date column and explicitly tell Numbers, in the Format&gt;Cell sidebar what the date format is.
I tell my students this: You will also enjoy using the YYYY-MM-DD date-format because it sorts correctly as mere text, even as numbers, while all other formats do not.