Earlier quoted context omitted.
Cookies are such a mess. We need cross-domain cookies. Google took them away so they could further entrench their analytics and ads platform. Abuse of monopoly power.
We use OAuth2 for identity. We use first-party cookies for session management. We use APIs and signed tokens (JWT) to federate across domains without leaking user data. The ones hurt by the death of third-party cookies are ad tech parasites who refused to innovate imho...
Also: tech should be easier, not harder.
Building this shouldn't take more than an hour, yet somehow we did this to ourselves.