DeathAdder 3.5G Stuck with Obsolete Synapse 2

I own a Razer DeathAdder 3.5G (Model No: RZ01-0015). Unfortunately, Synapse 3 does not support this mouse—only Synapse 2 does. However, Synapse 2 requires an account login every time it's used, even though it’s already reached its final version and is no longer officially supported. Why didn’t Razer remove the mandatory account login requirement in the last release of Synapse 2?
Even worse, Synapse 2 can’t even control basic features like toggling the lighting on the DeathAdder 3.5G anymore. It feels like Razer has completely abandoned its long-time users who still rely on older but perfectly functional hardware.