On a number of sites I am increasingly finding that I do all the work in Firefox (ordering, filling froms, filling text boxes) and can't complete the job because the final complete button does nothing. Slowly but surely I am having to switch to Chrome to do stuff, and I don't want to! The latest example is Ocado on which I've used FF for years. Now, Book a slot, fill trolley, "checkout" button doesn't work. (anybody can duplicate this). Even they know about it - it just started this week after "we have just changed our webpage".

What are all these sites doing that FF is not keeping up with ?