Increasing prices is not "pulling the rug out from under you". Hertzer decided to raise their prices. Their customers can either continue using their service, reduce their use of the service, or go somewhere else.

Also, we live in a time of high inflation. We should expect price increases because they value of the dollar, euro, etc. is going down.

> There are also some EC2 instance classes where upgrading instance types in the same "size" are more expensive

An increase in price has been the rule rather than the exception for recent upgrades for vanilla instance types, e.g., c, r, m types in the newest generations (6 -> 7 for x86, 6 -> 7, or -> 8 for Arm types).

The increases have been modest though, perhaps around 10%. You get additional CPU and sometimes minor increases in other resources on the newer types.