In the latest 2.18.74 beta, WhatsApp launcher icon is seen to be housed in differently shaped frames. Spotted by Android Police, the image shows the same WhatsApp icon housed in a square, a circle, a rounded square, a guitar-pick shape and so on. The actual icon on WhatsApp is the same in terms of design.
You can download the WhatsApp version 2.18.74 from the Google Play Store by joining the official beta or by downloading an APK Mirror.
Also, in more WhatsApp Stickers related news, WhatsApp has also enabled three new sticker packs titled Salty, Cuppy and Bibibmap Friends. This was spotted by WABetaInfo, as it has noted the recent update to WhatsApp servers with the 2.18.75 version.
Do note that Stickers Store has not officially been made available to WhatsApp users and WABetaInfo has not committed to any either, but it notes that translations are missing and WhatsApp does not enable any feature without translating it.
So there will be some time till we start seeing Sticker Packs on WhatsApp.