Because it's their release week, so there's multiple new products every day. The overlap of people using HN and Cloudflare is pretty large, so not that surprising.

A related Q: why are their products so popular? I get why CDN/DDOS protection is but what about everything else? I have never ever found a use for stuff like Workers. (Sincerely asking, not dismissing them as useless)

I suspect also to do with internal Slack etc. where employees vote on launch posts (a lot of them on HN since long). Not a scam or accusing anyone but this probably propels a lot.