If your Twitter doesn't look like it used to, it's not a bug. Twitter confirmed a big design change and users aren't so happy about it.

While previously, Twitter users had the ability to choose a look they prefer, selecting wallpapers and customized images to make their timeline more personal, the social network website has now introduced a more uniform look.

More specifically, Twitter removed each and every wallpaper from users' home and notifications timelines, without any prior warning or announcement. An all-white background now welcomes users instead of the customized backgrounds they used to have, lingering whether you're looking at your main timeline, your profile or your notifications.

"We're removing background images from the home and notifications timelines on Web for all users," a spokesperson for the company confirmed to Mashable. "Now, background images are only available where logged-in users will see them publicly (Tweet pages, list pages and collections pages). You can find help center content about customizing your design and where it's visible on Twitter here."

Considering that Twitter issued no official statement and announcement before proceeding with this integral design change, users were taken by surprise, and most of them are not pleased with this look at all.

Despite confirming the change, Twitter has still offered no reason for why it chose to go down this path, so the reasoning behind this design overhaul remains unknown for now.

While no official explanation is available at this point, Tech Crunch speculates that Twitter could aim to gain more control of its "ad display experience." In other words, Twitter may be gearing up to invade users' timelines with ad-based backgrounds.

This theory makes sense, as Twitter surely had a reason for removing all custom backgrounds and making everything bland and uniform. Given the increasing number of comments and complaints from users, however, the company should issue an official statement soon.

Currently, users have no way of changing back their feed or profile, but their own background will still appear on Twitter where "logged-in users will see them publicly."

It will be interesting to see how this move will affect Twitter's popularity and whether the social network will repel users instead of attracting more.