HashiCorp is the latest big name to do it—they switched to the BUSL, which more or less says you can only use the product if you aren't offering it for sale in competition with HashiCorp:
The entire codebase will be open-sourced a few years after a version is released.
You can use the old version and fix security vulnerabilities yourself. If you really want the latest features, you pay.
If they ever decide to enter your specific business they have an automatic kill switch on you.