A variation of the old (really old) Twitter logo is being used in various places on Area51 when sharing is involved:
This goes against Twitter's branding guidelines (which have been in place for at least 4 years now), which state:
USAGE GUIDELINES / IT’S A BIRD, NOT A PLANE
The Twitter marks represent the core values of our brand, from meaningful connections in real time to simple amplified expression. Please don’t present the marks in a manner that suggests sponsorship or endorsement by Twitter, or confuse Twitter with another brand. Always use our official and unmodified Twitter logo to represent Twitter.
- Use older versions of the logo, previous logos, or any marks that may be confused with the brand