The latest version of the Google+ Android app (version 10.1) brings with it a number of minor yet visually impacting changes. The Google Play Store listing states the updated version became available on March 6, 2018, and it is already confirmed as in the process of rolling out to devices. This follows on from another recent update to the Google+ app, although the previous update placed more of its focus on performance improvements and less on cosmetic changes.
Of the visual changes, the most notable one is the overall tendency to show white coloring. While the older version also did come with a significant degree of white throughout the interface, the current version has changed what was otherwise colored elements also white. This is best seen in the 'App bar' which up until now had adopted more of a red color synonymous with Google+ branding. Recently however, the red coloring on other platforms (such as desktop) had seen the red element replaced with white. This is also what has now happened to the mobile app version with the main red color at the top of the app's launch page now appearing white. As a result the only red coloring that can be seen when the app launches is the 'create new post' icon (which was red before) and the "Home" icon located as part of the bottom bar – which was not red before.
The reason the Home button icon has changed color (from the previous white) is the actual bottom bar itself has now also lost its black color in favor of white. Outside of the home tab, it seems color remains in place with the likes of the Collections and Communities pages retaining their original colors, while also their bottom bar icons gaining a matching color. Therefore the white changes will most readily be seen on the main page feed as well as when clicking on individual posts. Interestingly, while Google+ seems to be gearing much more towards a white color overall, Android has started to make use of more color. As Google has now released the first develop preview of Android P and with it comes more of an emphasis on color and especially within the settings menu.