Non-AI-code: forget it, you won't be able to avoid it in your libraries, and you won't write the whole engine from scratch.
It's possible to write a whole modern engine without it, but you won't, you'll spin wheels chasing features and never ship.
People don't care about your entire dependency chain, see how little the most valuable FOSS libraries recieve in donations or sponsorships compared to end-user apps. They care about how well put together your own app is, which we know AI use changes for the worst (which some argue is worth it for momentum).
As long as your dependencies aren't outright dysfunctional (see rsync debate), it's concensus to disregard AI use there.
Other distros ban use of LLMs. Not sure how that's going to go down given Linus seems to be willing to use them for the kernel.
I don't think it's avoidable (unless you stick to a pre-LLM game engine), but it's clearly an error to underestimate quite how much people really loathe this stuff.