Wiki macros are prepared at init but if a wiki macro use another wiki macro that happen to be initialized after a warning similar to the following might be produced:

2023-10-30 13:58:47,560 [XWiki initialization] WARN  .x.r.i.t.m.MacroTransformation - Failed to get the macro with identifier [wikis] for syntax [XWiki 2.0] (this macro block won't be prepared): MacroNotFoundException: No macro [wikis/xwiki/2.0] could be found.

The reason is that in this case the macro "wikis" was not yet initialized when the other macro was prepared.

A possible way to fix this would be to prepare a wiki macro the first time it's executed instead of at init. It also shows that we might want to invalidate the various cached prepared contents when a macro is registered/unregistered.