DeepSeek has introduced new “instant” and “expert” modes to its chatbot, the most significant update to its user interface since the Hangzhou-based start-up gained global recognition. The changes come ahead of the much-anticipated release of DeepSeek’s next-generation flagship model V4 this month, more than a year after its R1 version made it a household name. On Tuesday, the company added the two modes to its website and mobile app, giving users the choice of settings. Instant mode was designed...