TikTok's added a new feature to that download option: the ability for creators to download their videos without a TikTok watermark, thus making it easier to repurpose your short-form video clips within other apps.
TikTok is nudging users either to save your video with a watermark, or "post to save without watermark" when you tap on the "Save" option within the upload flow.

So basically, TikTok will allow the sharing of a video you post across other apps but first share it to TikTok. This way, it first ensures TikTok gets more content but also allows users to share the same in other applications.

Because if you add a watermarked clip to Instagram or Snapchat, it'll be limited, and YouTube might also limit that in Shorts, so if you're looking to repost that same clip on other apps, you don't want that watermark left visible.

TikTok has been allowing users to download clips without a watermark since early this year, although now it added the post first requirement. That'll check users who have been using TikTok's editing tools to make their clips but not uploading them on to the app.

While, technically, you could have accomplished this anyway, through CapCut, which is TikTok's native video editor. Still, for users who aren't using other edit apps, that makes it at least a little easier for TikTok to ensure that clips which start from its app end up on TikTok in the first place.

So instead of searching for loopholes to prevent the signs from the application, TikTok simplifies the task a little while working in its own interests too.
You can find the new save without watermark option in the Save menu in the latest version of the application.