I had success applying the following workaround:

(advice-add 'bash-ts-mode
            :after (lambda (&rest ignored)
                     (when-let ((bash-things (assq 'bash treesit-thing-settings)))
                       (setf (alist-get 'text (cdr bash-things)) '(sentence)))))

Now M-q does the right thing for me everywhere in bash-ts-mode.