TiddlyWiki’s wiki text reserves # for numbered lists, but only at the start of a new line. So, you could adopt a convention of preceding your hashtags with, say, a dot:
—
This is a note.
.#mytag #anothertag #and-another-tag
—
Another alternative is to disable the numbered list parse rule within your tiddlers:
—
\rules except list
This is a note.
#mytag #anothertag #and-another-tag
—
You can also use the Info/Advanced/Parsing tab of Control Panel to globally disable the list rule, but you may run into compatibility problems.
Generally, TiddlyWiki takes great care with backwards compatibility to increase the chances that people can freely upgrade from earlier versions. So, we couldn’t outright change the wiki text syntax, we can only extend it.
Best wishes
Jeremy