Instagram has made some fairly subtle changes to the look of their app, primarily adjusting the look of their call-to-action bar. The change has this section of the app looking more like their ads. The obvious intent here is to get people to click more ads by better blending them into the rest of the content on the site.
In the past, the call-to-action was a blue bar at the bottom of the image or video. With the update, the bar color will blend in with whatever the main colors are on the image. So, nature photos might have a CTA that is green compared to maybe a red or orange bar if the image were of a red dress or of fire.
Instagram says that the move is made to help ensure that the image or video is the stand out portion of the page, rather than the CTA bar.
This move also gives Instagram an option to place additional ads on their platform without it seeming over crowded to most users. This, of course, will help to boost their revenue, which is always a priority. For marketers, the move can provide a lot of benefits since integrating CTAs into the page naturally is a very effective way to boost clicks.