From today the license applied to the project will be the Apache 2.0 license with an extra line forbidding usage of the codebase as an integration or app to Atlassian's Confluence or Jira products....
TL;DR: Competitors in integrating with Atlassian are not allowed to incorporate code after the change because they used it in free add-ons, which caused the official integration (a paid add-on that is the sole source of funding) to be labeled a scam by a review in late August.
Plus, the thing was never really open source anyway:
draw.io is also closed to contributions, as it’s not open source. We follow a development process compliant with our SOC 2 Type II process. We do not have a mechanism where we can accept contributions from non-staff members.
TL;DR: Competitors in integrating with Atlassian are not allowed to incorporate code after the change because they used it in free add-ons, which caused the official integration (a paid add-on that is the sole source of funding) to be labeled a scam by a review in late August.
Plus, the thing was never really open source anyway: