Read more about it:
Expanded possibilities for larger deployments, improved file sharing options, more intuitive management, and major package updates come together in a DSM that is easier than ever to monitor and protect.
Discussion thread for version 7.1.42621 (RC) already available:
Differences are bold compared to the previous 7.1 beta (2022-03-24) Important notes This update will restart your Synology NAS. After installing this update, you will not be able to downgrade to a previous DSM version. For the following models, DSM 7.1 will be the last upgradable version. XS...