Clever for the example to be lowering prices when we know they are going to use this to squeeze us.
Is there a path forward that doesn't involve a class war?
Best way to stop this is something like the FTC stepping in. Honestly, this is mostly likely illegal in the context of a grocery store.
If I walk up to a shelf, grab an item advertised at $1, then when I get to the checkout stand it's actually $2, you've now mislead me on the price with no ability for me to have verified the price.
Now, without getting the law involved, one thing you can do is simply make it too expensive for these stores to switch prices. Take a picture of the price when you grab an item (annoying I know) and if you get to the exit and the price is higher, reject it and have the grocer take it back.
If you don't want to do this with everything, primarily target refrigerated foods which they HAVE to throw out if you give it back to them (And they have to take it back).
In Australia, if you see an item had scanned for more than the price advertised on the shelf, you get it free. I've seen it in action a few times in my life. Last one was a savvy teenager who saw his bottle of coke was higher and he called it. He got it free.
When I worked at a grocery store (a bit over a year ago) we had a sign posted near the registers, though in a place it was easy to not notice, stating something similar, though it might have been a state law (MA) rather than anything federal.
I've seen grocery stores with digital price thingies on the shelf in front of the items before. They'll probably switch to that it it ever became a legal issue. Some people, not me, would suggest, though I would never, that breaking those and shoplifting would be good and ethical responses to such activity. In theory. I'd never suggest that, though. All that businesses do is good, and a hundred quantbrillion lifted out of poverty and blah blah blah flag waving gif
We live in perpetual class occupation precisely because the owner class has never had a problem assaulting the lower classes, while the lower classes argue about how unseemly and unfair it would be to fight back.
The path forward not involving the peasants actually fighting back for once is just more of the same, the owner class leveraging their capital/power/governmental capture to get more for themselves by finding new and interesting ways to exploit you.
No, there is no way forward with any hope that doesn't involve class war. Fortunately for the owners, their divisive propaganda is working as intended. We're more interested in fighting one another over social wedge issues, largely exacerbated by economic inequity btw(more peasant income, for example, would mean fewer abortions without bans as abortion is often, obviously, and understandably an ECONOMIC decision), than our common enemies at the top. Until we stop looking for fellow peasants to blame for our problems and start looking upward at the root cause, there is no hope.