To be fair to Loblaws, I've never seen them change prices with these mid-day, so they're not engaged in "surge pricing" that I've heard of. (I haven't been to Loblaws since the start of the boycott, but I don't expect it's changed.)
But I do wonder about the legality of that; right now, if the price at the till doesn't match the item price, you get the first one free and the rest at the marked price (up to $10 items; above that it's $10 off the marked price for the first item). But my impression is that policy is from Loblaws signing some sort of grocery code ages ago when scanners came in, essentially to assure consumers that they wouldn't be scammed by scanners ringing up items at higher prices than advertised. I don't think that is legally mandated.
So, then, what happens if the price changes between when you put it in your cart and when you arrive at the till? Anyone engaging in surge pricing where the timing isn't clearly marked in advance is going to get into a lot of trouble with consumer backlash, at the very least, but I hope it's illegal, too.