Typically I wouldn't think so because there is an F in FOSS, after all. However, they explicitly say that they worked with him, so I would imagine it was paid time.

Disclaimer: I have no connection to Stripe (aside from wishing I had gotten pc's username first!) so I'm just guessing.

I wrote the package because I needed it. My compensation came when my package worked and I could use it. Since then it was just a "cost" because I chose to maintain it for the community. Like most of us I write software for money, too, but in this case the stripe package was just "collateral benefit" from something else I was doing.

I didn't have time to do the cleanups and rewrite that the package deserved to get support for the new Stripe features with a consistent API.

I haven't been needing the new features myself, so honestly I was delighted when they asked months ago if they could take it over. For them and for the community it was better this way than if they'd just forked it or just published another package.