The chances may be small, but to quote the war of the worlds "still they came".
My own limited experience is that some green oak that I have bought from Eastern France, despite bing in open air and sticked for several months, can still exhibit these annoying yellow patches and streaks.
The other issue commonly found, again in my limited experience, is that where oak has been stored in stick ( I am talking about anything up to 8" beams here, which is the largest I have ever bought) can acquire quite deep black staining from the oak offcuts typically used as sticks.
I know yellow stain has been evident for at least the last two decades, but it seems to be getting more common. I always thought it was due to poor kilning practices (rushing basically), but good timber merchants know that discerning customers will reject badly kilned stock and so it surprises me that anyone would take this risk.
All of my home grown oak in store has never been near a kiln and none of the stock I have used or sold has ever shown this phenomenon.
I've got some yellow stained oak at the moment that I bought from a supplier I have not used before (it is machined for floor boards). In present circumstances the supplier would rather write it off (nearly 40% of the order) than collect it as a return in present circumstances. I plan to experiment with bleaching and oxalic asset treatment just to see what happens.
For interest, I also think that Wenge I have bought recently from one source (never used before) is abysmal quality compared with what I used to get or indeed what I bought last year from my favoured supplier in Tonbridge. Same supplier shipped some walnut (not much) that I don't think is English walnut. We are having a little chat about proof and source.