The "they'll mold perfectly" narrative is kind of oversold - Birkenstocks do adapt somewhat, but they're genuinely not for everyone, and some people's feet just don't click with that particular arch support style. A month in with soreness after a few hours suggests either they're not the right fit for your foot shape, or you're ramping up wear time too fast. The molding process typically takes a couple months of regular wearing (like a few hours daily), but that's assuming your feet actually want to work with the design - some people never get comfortable because the cork and footbed are too rigid or the arch placement doesn't match their natural gait. If your feet are still actively hurting rather than just feeling "broken in," you might want to try insoles or consider that Birkenstocks might just not be your brand, which is totally fine.