Hello,
I'm a regular engineer by day. By night, I work on a few open source and non-profit projects. Some of these incur recurring server, domain name, and storage costs. It's my goal those projects remain accessible and available for free forever. I won't ever charge for them. That said, these costs add up over time and performance is often bottle-necked based on how much I can personally afford to spare. Stewarding these projects is far more sustainable in the long-term when it doesn't need to depend on my continued sponsorship.