I can't tell you excatly why rates go up except to say that we live in a highly complex world economy. I live in California where everything has gone up & continues to go up. Thank you very much Donald Trump! And don't forget to vote this November.
At Amazon prices depend on the time of the day, the device you use to buy and the number of items still available...and some very obscure factors.
I suppose that Adobe has determined that the profit margin at the former price tag was no more enough.
https://www.digitalartsonline.co.uk/news/creative-software/adobe-price-increase-confuses-customers/
https://prodesigntools.com/creative-cloud-prepaid-discount.html
Oh and btw: Going voting is in my country a legal obligation.