When you right-click a Paragraph Style in the Styles side-bar in LO Writer, you can Modify it.
However, if you do the same for a Table Style, you _can't_ modify it. Why? You should be able to.
To give exact version info:
Version: 18.104.22.168 / LibreOffice Community
Build ID: 094b4116e8de6d2085e9b65d26912d6eac4c74a9
CPU threads: 4; OS: Linux 5.9; UI render: default; VCL: gtk3
Locale: he-IL (en_IL); UI: en-US
Please don't forget to CC @libreoffice-ux-advise when using the keyword needsUXEval.
*** This bug has been marked as a duplicate of bug 105933 ***