Select the cells, right click, Format cells, Fomat tab, set language to None.
EDIT after comment by reg4arz: filed a bug report, see https://bugs.documentfoundation.org//show_bug.cgi?id=101973
EDIT 4th Oct: reply to bug report: “When applying formatting in Calc, it’s good to realize that there is a difference in doing that to a cell or to strings in a cell.
With that in mind: edit the cell, select text and again set to no language.
(I did it with Format > Character)”
Haven’t checked yet if that helps.