like many people have said this better than me but no it IS odd that we've come to think of potatoes as so quintessentially european that their presence in historical fantasy where they're anachronistic doesn't jar. and yes people are trying to have the trappings of post-colonial europe without engaging w the icky colonialism part and yes people are neglecting to imagine what a european cuisine without potatoes would be like.
im fully in favour of 'let people have fun w their fantasy world' but is considering how the potatoes got there in the absence of colonialism not a fun exercise? maybe every year the dragon riders go on a great transatlantic potato pilgrimage
perhaps a good way to sum up the issue here is:
if you put potatoes in your medieval european style fantasy world people will by and large not find it jarring and accept it as a normal fantasy trope
if you put, say, black people in your medieval european style fantasy world a whole demographic of people will get very angry and accuse you of breaking their immersion
this is in spite of the fact that black people were a lot more common in medieval europe than potatoes.
