SOL left behind by failed deploys
Deploying a Solana program uploads it to a buffer account first. If the deploy fails, the buffer stays behind holding the rent for the whole program, often several SOL, and nothing ever cleans it up.
Why this happens
A program is too big for one transaction, so the toolchain writes it into a buffer account in pieces, then deploys from that buffer. A successful deploy consumes the buffer. A failed one, an interrupted upload, or a machine that went to sleep leaves it sitting there, rent-exempt and forgotten.
The rent is proportional to the size of the program, so a large program can leave several SOL in a single abandoned buffer. Anyone who has run solana program deploy and watched it fail is worth checking.
What this signs
One instruction per buffer, the standard loader Close, sending the deposit to you. Stake accounts use the standard Withdraw. There is no DustJar program involved and nothing here can touch a program you are still running: the security page lists every instruction.