If not, I think it's clear that you should not contribute, but it's not as clear.
So, it's clear but not as clear...
The OP has a modest mortgage balance, on a cheap tracker, and has an ample cash reserve to address almost any conceivable uninsured emergency that might arise.
In these circumstances, I would have thought it was pretty obvious that increasing pension contributions, rather than paying down the tracker mortgage or investing outside a tax advantaged wrapper, was easily the better option regardless of whether or not the OP pays income tax at the higher rate.
Based on everything we know today, all the pension contributions have to do is produce an average net annualised return of at least 1.35% over the ECB refi rate over the next 27 years to come out ahead. To put that modest level of return into context, Zurich's Balanced Fund has produced an annualised reaturn of 10.5% (before deduction of AMC) since 1989.
Also bear in mind that the pension contributions will have a 20% head start over paying down the mortgage if the contributions are relieved at the standard rate and a 40% head start if the contributions are relieved at the higher rate of income tax.
Yes, any pension drawdowns will be subject to income tax at some unknown rate in the future. But on the basis of today's tax rules, the accumulated pension pot would have to be pretty substantial (over €1million) before any income tax actually bites (although USC may take a nibble), assuming the OP retires at 65 or older.
I also suspect the OP is still entitled to MIR for the next couple of years, which skews the decision even further in favour of contributing to a pension before paying down the mortgage.