Was it sold as a "lifetime" licence with free upgraded to future versions? I suspect not. A perpetual licence to 1Password 7 is just that, a perpetual licence to that version of 1Password. 1Password 7 will still work, and the only reason the extension will stop working is due to Chrome dropping support for Manifest V2. Would you be complaining if the desktop application stopped working due to updates to your OS?
C’mon man, you can’t be serious. A password manager without a browser extension is a useless password manager. And please note that 1Password7 extension will stop working, not the newer version…
That's because the 1Password Classic extension is tied to the 1Password 7 desktop app, whereas the new 1Password X extension is more standalone (and only supports cloud vaults). Because 1Password 8 also only supports cloud vaults, there wouldn't have been any reason to support the 1Password Classic extension on 1Password 8, hence support for that is similar to support for 1Password 7 (i.e. they won't be moving to Manifest V3 for it, as it's not the current version anymore).
Would it have been nice for 1Password 8 to support local vaults, or 1Password X to support accessing local vaults from 1Password 7? Yes, but they're hardly under any obligation to do so. The simple fact is 1Password 7 is an older version, so isn't getting major updates. As 1Password Classic is only for 1Password 7, neither does it. It's an older version, not fully supported anymore, so it's not going to get a port to Manifest V3. Admittedly, I have no idea how much work that would even be, but it's hardly something that is expected for an old version.
I doubt there would be as much fuss over this if 1Password 8 supported local vaults and had a perpetual licence. This is just the normal case of old versions of things no longer working on newer software. The fact that 1Password dropped support for local vaults in newer versions is beside the point, and another thing entirely.
