Maybe that means we don’t need version 5? Companies aren’t supposed to be immortal.
But there's many "security flaws" that are nowhere near critical or just don't apply to your use-case for the software.
Not to mention local-first software has much less attack surface for pwnage. You can wrap insecure protocols with encrypted tunnels, you can share files from a legacy app with any secure file transfer app of your choice... or if all you need is local functionality you don't need to share at all which means no remote access possible.