I've been accumulating bitcoin into a paper wallet for a couple weeks. It's all been stolen. I'm trying to figure out what I did wrong: https://www.blockchain.com/btc/address/193jdrxMKoUjWLyKm2UCGNXLGGvK1x3FDV
I've been very careful with this wallet. I purchased bitcoin on Bisq. Over time I was sending them to a paper wallet that I generated on bitcoinpaperwallet .com. I printed this paper wallet on a piece of paper hidden inside my house. I never saved the private key anywhere on my computer.
As I transferred funds into the wallet, I would verify they arrived by checking blockchain .com. They always did.
A week ago I transferred a lot more bitcoin to this same paper wallet. Today I checked and the wallet was completely drained, hours after the last transfer and soon after I verified they arrived (using blockchain .com). The bitcoins seem to have been instantly transferred to a bunch of wallets downstream and scrambled.
I'm completely baffled as to what I've done wrong. I searched my computer to make sure I didn't accidentally save the private key somewhere, it's nowhere to be found. But I knew that I didn't do this. I was very careful when generating the paper wallet. The only place the private key is on this piece of paper.
No one in my house knows anything about bitcoin, and anyway, this paper has been kept concealed.
What did I do wrong? Any clues?
P.S. Since I know someone will ask, the reason I didn't use a hardware wallet is that I was going to save this paper wallet on multiple encrypted USB sticks. I don't trust the hardware wallets to be secure and recoverable ~10 years from now when those companies may be gone and their software may be outdated.