When defining the table, or afterward, you need to make sure that the "autofit to contents" option is set for all cells in the table under the AutoFit option, and that up in the paragraph formatting area that you have center justification selected for all cells as well.
I generally select the whole table, do the Autofit setting, unselect the table then select the whole thing again, then apply the text centering in paragraph. You can try doing both, and it will often work just fine, but sometimes not. If it does, you've lost nothing by trying to kill both birds with one stone, and if it doesn't, and you apply those settings in the order I've mentioned, you know that it's the centering in the cell that you need to apply after having selected the table again.
The above applies regardless of the version of Word/Office. These are table formatting tasks in Word. They also have nothing to do with what particular screen reader one might be using at the time.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
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