If I remember correctly from Shai-Hulud 2, the attacker extricated creds by posting them in public github repos with minor easily reversible encryption. I believe it was double b64 last time.
I'm assuming the logic there is that every security researcher and company is going to pull and scan those creds for their stuff and their clients' stuff. So the attacker is just 1 of N people downloading it. As opposed to trying to send it to their own machine directly.
If they have a clue, the attacker still will not download that without using a botnet tunnel or Tor at a minimum.
Note though that these credentials aren't even encrypted using some lightweight ECC to prevent others from capturing them, they're posted in cleartext. Embarassment might be part of the point.
The public repo path is just one of four parallel paths, with the goal of getting around any barriers:
The exfiltration component shares its design with the "Mini Shai-Hulud" mechanism from their last campaign, using four parallel channels so stolen data gets out even if individual paths are blocked.