In all the talk about the Marr/Morrissey relationship, there really needs to be a distinction between the period before 2017 and the period after.
In the period before, although things were a little awkward there was always a chance they could work together again and as we know, it nearly happened around 2008. But from 2017 onwards when Morrissey officially endorsed/supported/defended a bunch of right to far-right wing wankers (For Britain, Farage, Le Pen, Tommy Robinson), there really is zero chance of Marr ever wanting to work with him again, unless Morrissey issues some massive retraction and expression of remorse for the foolishness of his political comments and actions.
Added to this that Marr's solo career (of which I'm not a huge fan) has gone from strength to strength in recent years, there is less reason than ever for Marr to work again with Morrissey. The amazing thing is that in the 2020s, you're now more likely to hear a new song on the radio being sung by the guitarist from the Smiths than by the singer.
My usual disclaimer is that Morrissey does not hold consistently right wing views, having expressed support for a few non-right wing politicians too. But unfortunately, his endorsement of For Britain was so clear and unambiguous, that this is what has stuck in people's minds and can always be easily referenced/quoted in any discussions about him until that endorsement is removed. Simply saying "I have never voted" changes nothing.