thank you all. Replies to your comments:
I've tried numerous imports with variations::
AFPUB with no accents, with different name
save the data file xlsx with a different name
Inverse column B with A (the problem is not the column but the date)
put a different year-date
Write real values in all column formated as 2023-01-01, OR put formulas like B=A+1, C=B+1, etc.)
in all cases, I get minus 1 for the date written in YYYY-MM-DD in every column.
I GET GOOD RESULTS if I use the format which is not our standard in French: DD-MM-YYYY.
if I import the datas in CSV, the A value is EXACT in AFPUB but I don't find CSV option as interesting.