I have found a solution to this problem.

This keymapping was coming from the spacemacs org-mode layer:
https://github.com/syl20bnr/spacemacs/blob/bd7ef98e4c35fd87538dd2a81356cc83f5fdi02f3/layers/%2Bemacs/org/local/evil-org/evil-org.el#L134

In my init, this mapping can also be over-written to `evil-next-line`:

  (evil-define-key 'normal evil-org-mode-map "t" 'evil-next-line)

-Brandon.