https://pbs.twimg.com/media/EVlSHCjWAAIELXW.jpg
Fifteen char alpha-numeric filenames (incl. some characters like "_") are the way twatter encodes their filename depending on time/date, processing center and userID (funny enough, called snowflake-algorithm).
Same goes for "D4_NNuzX4AAJjxS""
https://www.hackerfactor.com/blog/index.php?/archives/634-Name-Dropping.html