I've seen exactly this behavior on claude.com with no system prompt with Opus 4.8 specifically, especially around chronic illness stuff where there's establishe

I've seen exactly this behavior on claude.com with no system prompt with Opus 4.8 specifically, especially around chronic illness stuff where there's established mainstream medicine dogma and reddit / internet communities with alternate causality theories and treatment approaches (PMDD and MCAS-adjacent illness). 4.6 is happy to analyze and consider them, 4.8 really doesn't like the alternate theories and treatments.