To provide a good answer you would need to share more of your insights.
Why was it a no-brainer last year but not anymore? And why would it be different to holding index funds or shares elsewhere?
How will you determine that it touches the bottom?
Same as before, max amount paid in annually, invested in max equity. Every few years I will decide whether to repay mortgage with it, taking into account the funds development and interest rates. In that case, I will switch to cash until withdrawal but continue to make my annual payment. But the timeline is years, even decades, not months.