This is what I came to say. If you want to undermine open source software, you undermine the maintainers who hold it all together. Swamp them in pull requests, some that are genuine, some with subtle bugs, some that are nonsense. Also try to start flame wars and circulate unsavory rumours about them, claim they are sexist, ableist, racist, or that they are trying to capture the software fir big business, or anything else that might drive a wedge between them and their community. Ideally, drive them out of OSS entirely and encourage a large enough portion of their audience to switch to a fork you maintain through a sock puppet account. At that point you control the software, regardless of the OSS tag on it, and can go about degrading it slowly.