Data-driven and last-click models allocate credit differently. GA4 currently offers data-driven, paid and organic last click, and Google paid channels last click models; check which reporting contexts each applies to.
First-click, linear, time-decay, and position-based models are no longer GA4 options. It is incorrect to say that all rule-based models disappeared or that every model universally requires 300 conversions to operate.
Reporting attribution settings affect metrics and dimensions differently from user- and session-scoped attribution. Before comparing a setting change, check the official scope rules and record the settings used for each report.