Serious adult language learners trapped by Duolingo energy system that cuts off practice after 3 lessons

Duolingo replaced its hearts system with an energy bar that drains after 3 perfect lessons, forcing users to wait 18 hours, spend saved gems, or watch ads to continue. Long-term users with 700+ day streaks are abandoning the app. The core painpoint: every serious language learning app either gamifies to the point of being useless for deep study (Duolingo) or is desktop-only/expensive (Anki, Babbel, Pimsleur). There is no mobile-first app that gives serious adult learners unlimited daily practice with spaced repetition, grammar explanations, and conversation drills without an energy mechanic or gamification trap. Post-energy-system revolt, users flooded r/duolingo asking for alternatives and found nothing satisfying for intensive mobile study.