First off, you will retain the trust gained from the VRC+ trust boost and any "Early Supporter" statuses or badges.  As for what you will no longer have access to, you will have your user icon unselected and cleared, and while Vrchat will save your uploaded photos and icons, you will not be able to use or swap to them until you re-enable your subscription.  Similarly, you will lose access to your VRC+ granted rows of favorite avatars. However, you will keep access to the first 25 favorite avatars in the first row, while Vrchat will store the data for the three VRC+ granted rows should you restart your subscription.