Yeah; citation needed. I've never seen an instance of a price increase. I can find multiple forums of people claiming Amazon has never increased prices.
The only instance I can find of any cloud provider increasing prices was once in 2015 when Microsoft did in Europe...and while that led to a flurry of "cloud providers are going to increase prices" blog posts and things, calmer heads noted the exchange rates as the likely reason (and, certainly, the claims that prices would increase across the board never came to pass).