Do they have the right to do that? Do customers in any country have a right to demand a product's firmware be restored to factory-state (on the grounds that what they received isn't what they were sold)?

I’ve used Australian consumer affairs laws to return products well outside the return date when they’ve been updated to remove/modify features I specifically wanted.

I returned a Bose speaker when it stopped letting you cast to it without their app, and have returned my Ring external camera when they removed customisable motion zones (I need to block a specific tree that moves in the wind). Plus more.

I’ve never had a problem doing so, I’m always polite and just explain that it’s no longer as advertised and print out the product update notes showing that they removed/changed x or y feature.

Even though if customers do have that right, I'd like to see how many % of the regular users actually demand it.

You have no idea how much I want Apple to be forced to allow me to restore my iPhone to its original firmware!

Sure, but we're on HN. The discussion here definitely doesn't reflect the general audience where 99% of the people aren't tech savvy and don't even know what a firmware is.

That's especially funny because Samsung TVs don't get feature updates.