The main goal of Twitter these days is to add more focus to lists and topics. Last 19 December 2020, they added a new card format when sharing Twitter list URLs. Such previews include colorful visual headers randomly generated. Today, the platform adds the option to customize a Twitter list header image. A user can now upload his banner image when he creates or edits a list. Just add a photo on the top frame to create a personal touch.

Twitter iOS and Web users can do such updates starting 28 May 2020, with Android users to follow soon.
Implications for Marketers:
Customizing a Twitter list header image is a minor part of Twitter’s larger focus. But it adds another element for users to discover profiles. As such, this can be a way for marketers to improve reach and engagement. Brands can use this perspective to excite the audience’s eye. The more visually appealing your header is, the more likely for people to visit your page.
Reference: https://twitter.com/TwitterSupport/status/1265694616256462848