Fuck that. It's the World Cup. You are allowed. Anyone who thinks this in the middle of the WC is completely batshit in their own right and not worth listening.
Normal people don't have to prove their political allegiances whilst waving a flag for a month.
It's "the rules".
I can't stand Reform, however I have an England flag in the drawer which I've had 20 years. It's been to Australia with me for the Rugby World Cup there when we won. It is brought out at appropriate times before tears and being put away again.