More hints are piling up that Twitter's service TweetDeck, which is currently free, could become a paid feature that's part of a Twitter Blue subscription.

The possible shift was noted by Twitter tipster Jane Manchun Wong, who has a track record of unearthing features in the code of apps before they're officially announced. Earlier this month, Manchun Wong tweeted about code that restricts access to TweetDeck based on a user's subscription status with Twitter Blue. 

On Wednesday, Manchun Wong tweeted screenshots of a homepage for TweetDeck that Twitter appears to be building, noting options to access a "legacy version of TweetDeck" and an "ad-free experience." These options don't appear on the current TweetDeck homepage.

Twitter users who pay for Twitter Blue can undo tweets, read ad-free news from more than 45 sites and get early access to experimental features, among other perks. A subscription costs $3 a month. It was available in Canada and Australia in June, but has since rolled out to other locations, including the US and New Zealand in November.

Any changes to TweetDeck haven't been corroborated or acknowledged by Twitter. When asked for comment, a company spokesperson replied, "Nothing to share on this at the moment, but will let you know if/when that changes."