Nvidia only announced the "vanilla" RTX 3070 models with the official Ampere gaming GPUs reveal, but Lenovo's specs of the upcoming Legion T7/T5 desktop systems clearly show Ti versions with 16 GB and Super variants with 8 GB. This may be a mere miscommunication issue between Nvidia and Lenovo, or it could be that Lenovo is planning to launch refreshed GPUs versions later on.
https://www.notebookcheck.net/Unannounced-Ti-16-GB-and-Super-8-GB-versions-for-the-Nvidia-RTX-3070-GPU-pop-up-in-Lenovo-Legion-T7-T5-desktop-specs.491376.0.html