After Cloudflare's announcement this is likely a last act as people move away. Good luck if you invest but I can see them filing for bankruptcy in 2-5 years.
Backblaze makes 73% of their revenue from computer backups. I do not see how the Cloudflare announcement will eat into that. I would agree that B2 is their high growth area, but I do not think Cloudflare directly opposes B2.
I don't think they're targeting Backblaze, but their position as the foremost middleman of the Internet means they're going to hurt direct competitors and partners pretty much any time they launch a product, until they're out of partners that host "cloud services". Which is a position Cloudflare put themselves in entirely on purpose.