What does this new icon mean?

I'm wondering what this new icon means. The number, border and colors change size and shape between players.

Solution 1:

That icon shows a player's Endorsement level, while the colours represent how many endorsements of each kind that player has received:

• Sportsmanship in green
• Good Teammate in purple
• Shot Caller in orange

You can endorse other players at any time after a quick play or competitive match has ended but before ending the next match that allows endorsements.

Some arcade game modes also support endorsements, in both competitive and non-competitive versions:

• 3v3 Group Elimination
• Capture the Flag
• Lúcio Ball
• Team Deathmatch

For more information, visit the official website's page on endorsements.