Tinderbox uses underlying Apple frameworks to automatically create 'smart' links where URLs are detected in $Text. Automatic detection of such URLs i is now enabled by default. It can be disabled using Edit ▸ Substitutions ▸ Smart Links. The setting apples to all notes rather than per-note.
From v6.3.0, the status of automatic URL detection is now saved with the document and will be restored when the document is reopened.
From v6.3.1, templates ignore the smart Links settings as such link creation is unwanted in a template context.