“ It's not "politically motivated" because it was then-attorney general Barr who appointed Durham.”
I think it's pretty clear that Trump was increasingly displeased with Barr's performance as attorney general in the last few months.
And that the evasion and delay of an actual investigation happened with Durham's predecessor, and continues now. If Durham's investigation were politically motivated, his report would have been released 6 to 12 months before the Nov 2020 election, to benefit Trump.