Op are you making the mistake of thinking the house is actually what you can afford?
the house that sold in 21 is not the same as this house, from the plot being more overlooked, smaller, no conservatory etc,
this house was last sold 11 years ago for 426, so likely the price is in the ball park, maybe a bit less, but not where you are.
id urge you to look at house both in your budget and say 50 grand above, when you start to get into 100 to 150 k more you are highly unlikely to ever achieve that and always be disappointed.
in addition a house is only worth what someone is willing to pay , so someone else may well offer much more, ultimately though it’s irrelevant, no one is entitled to the house and the owners can stay in it and reject any offer they please,