Calc chart behaves strangely

I have a simple Calc table with Col A being a date and Col B containing related data (simple number). I have made a basic line chart to show how the data changes. When the x-axis gets beyond a certain point (in this case, 122 rows), the chart forces the start point to the date in row 123 and crushes the remaining data aginst the right axis. See file attached.
I can’t determine what is causing this behavour. chart behaviour.ods

Upload your file. (/upfiles/16038583957277471.ods) does not link to any. Try again.

Done - sorry!

It looks like a typo, cell A123 is 08/09/2000, it should read 08/09/2020. Might be worth changing formatting to show year. Cheers, Al

@kiwi_writer - are you aware that format of labels and format of the raw data can be set independently? Select your axis and Right click -> Format Axis... -Tab: Numbers and deselect option [x] Source format. Now you can select the format of the data, how they should appear on the chart without changing the format of the raw data.

Thanks Al - never occurred to me to check the full date!
Opaque - thanks for the pointer on deselcting Source format.