I don’t think “the number moves to the right”. You have inconsistent formatting in this column: the top cell has no padding, while the cells below it have 0.1cm all around. Your numbers are then badly positioned from the start.
Alignment in tabular data is better achieved with the use of a specific paragraph style defining tab stops. Tabulators have various properties. You can request a right-aligned tabulator where the right-hand side of text (in Writer tables, all data is text, even if made of numbers) will be flushed against the stop (instead of left-hand side. In case you have decimals, alignment can be made on the character separating the integral from the decimal part. This separator can be chosen at your taste, so that the feature can be used for other data than numbers.
By using such a custom paragraph style, you guarantee that all your cells will look the same, provided of course that the geometry defined by Borders
tab in the table configuration is the same for all celss.
PS: don’t use extra spaces after data. It matters when you have right-alignment or justification. Width of spaces can be adjusted by Writer and you never know the size.
Here: Fedora 39 (Linux), LO 7.6.3.1, KDE Plasma desktop (It is recommended to always mention OS and LO version).