Man, I hate it when documentation is not clear and/or inconsistent.
From https://tiddlywiki.com/#Variables and my understanding from the beginning for variables and macros:
By themselves, the snippets are not parsed as WikiText. However, a variable reference will transclude a snippet into a context where WikiText parsing may be occurring. Within a snippet, the only markup detected is $name$
for a macro parameter transclusion and $(name)$
for a variable transclusion.
But that is bunk. True for macros, but not for variables. Case in point, the following sample code:
\define thisYear2() <<now "YYYY">>
<$vars thisYear1=<<now "YYYY">>>
text widget results: <$text text=<<thisYear1>>/>, <$text text=<<thisYear2>>/>
direct reference results: <<thisYear1>> , <<thisYear2>>
</$vars>
Results in:
text widget results: 2023, <<now "YYYY">>
direct reference results: 2023 , 2023
So contrary to the documentation, variables do not behave like macros.