SVN updates (for all versions of Tiki) will stop in January 2023. This coincides with when Tiki18 reaches end of life. However, even if you use another version (like Tiki 21x) from SVN, you will stop getting updates because the Git and SVN combined workflow will be retired. You should get your updates from Git. See also: Tiki Version control history.
You can subscribe here: https://sourceforge.net/projects/tikiwiki/lists/tikiwiki-cvs
For historical reasons, it's called cvs, and it's not worth the hassle to change it. Ref.: Tiki Version control history
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