I'm guessing Parallels' customer base is getting smaller while getting Windows to work well on Apple Silicon is harder. A price increase was inevitable. There are many other options available for mac users who need to run windows apps - continue using an intel mac, other virtualization software, cloud-hosted windows, and separate windows hardware. Each has advantages and drawbacks depending on use case. Some users may find that ARM Windows doesn't support the legacy software and hardware that are the reason they installed Windows in the first place.
Parallels has long been the most convenient virtualization option. It will still be the best choice for users who need to use mac and windows apps simultaneously or have both platforms on the same laptop to use in the field, etc. For many though, cloud-hosted windows (you can even go hourly on AWS WorkSpaces if your needs are light), or separate hardware will be more attractive with the new pricing.