Recently I stumbled upon the sponsors of the 21st Debian Conference have a look:
You said all there is to say, not all big tech are straight up evil. I mean the world is more grayish than dark or white. Very good for debian to have some support from companies.They sponsor it because they use the tech Debian develops. If they have a problem with that tech, this sort of stuff makes for good investments. My company used to sponsor a few opensource projects, well over a decade and a half ago. Why? I wanted to support those projects because we used those products. I also want a patch ASAP when we find a problem, even if outside the normal release channels.
It's also a form of advertisement. We'd happily sponsor a few conventions and I'd even send employees to speak at the events. We weren't advertising for customers so much as we were advertising our employment opportunities.
Heck, I wanted the best of the best. I'd sponsor research projects at a couple of universities and then poach the people who worked on the projects. This is pretty normal behavior and there's nothing sinister or malicious about it.