Indeed:
> Audacity's source code is currently released under the GNU General Public License version 2 (GPLv2). We intend to update the license to GPLv3 to enable support for new technologies not compatible with GPLv2 (i.e. - VST3, which is compatible with GPLv3).
VST3 is dual licensed with some Steinberg license and GPLv3. The purpose of the CLA was to be able to migrate Audacity binaries to GPLv3 with VST3 support. This has happened as of Audacity 3.2.
Other uses for the CLA are to publish the thing in app stores down the road. It's not stopping Audacity being open source, unless you consider Apache software not open source.