Why do I keep getting free GTA V money from Rockstar? Is it safe to use?
Sometimes Rockstar offer rebates on shark card purchases or for items a player has purchased that once cost money but are now free. I believe they've done it before to apologise for server downtime, and then sometimes they just give money away for free.
Feel free to spend they money you've received. I received $500,000 recently myself just because they felt like it.