I don't care which either, that's why I elided the example in the comment I replied to - just to be clear I wasn't objecting to that in particular.
In the UK flying a union flag (residentially) would be extremely unusual - I'm aware of one, not where I live, and indeed it attracts scoffs and eyerolls - you do see England flags (St George crosses) more, particularly at certain times of year or certain years; that's more a signal that 'I am a football fan' than of patriotism, though.
Maybe that biases me against them in general. But even for things I do 'support' in some sense (I noticed a Ukraine flag covering a garage door recently, for example) I don't want a flag waved at me, and I wouldn't want a neighbour that did that.