Linux

I said a near-monopoly. Also, even if it's foss, by creating the format, they established the baseline parameters of that format.

That gives them a significant degree of control.

Edit: I also hate it because so many of the programs I use don't support it, so I constantly have to copy > paste into image editor program > Save as PNG.

Though admittedly this is mostly an adoption thing. Still, it's a major problem.

Google has discovered that FOSS software under their full control is better than pure proprietary software for monopoly abuse and rent seeking. With FOSS software, they enjoy the automatic popularity that they otherwise would have had to market very hard for. At the same time, none of Google's free software is truly free. Google devs regularly neglect and reject overwhelming user requirements (jpegxl in chrome is probably the best example of this) and choose designs that clearly favor the company monetarily. It isn't even practical for normal people to fork their projects.

Google often uses their 'FOSS' projects to twist open standards or the market to their advantage. Android and Chrome are very significant players in this regard. Using Chrome, Google even managed to make the W3C standard too complicated for others to make alternative browsers easily. Google has similar ambitions in the multimedia market. They want to replace the monopolistic media formats with quasi-monopolistic formats like webp and av1 instead of truly open ones like jpegxl.