Yarn v1 is being used in all the accelerators today as the de facto package manager for any frontend packages.
However Yarn v1 is deprecated and frozen from any new updates (security or fixes included). So it would be benificial to switch to using NPM or another modern package manager like PNPM. (see https://github.com/yarnpkg/yarn).
In the React accelerator it is a pretty smooth switch over to NPM or PNPM. But for the MVC Accelerator it doesn't work as there is a peer dependency mismatch and even if the error about peer deps is ignored with the --legacy-peer-deps flag. The Angular build fails anyways.
As of the 8.15 release this is now possible manually as the switch to Angular 17 makes it possible to use PNPM. NPM doesn't not work due to an issue with a angular dependency. But will probably be fixed shortly.