The TSSOP package and 003 in the part number suggest that these chips are meant to be a drop-in replacement for the STM8S003 "value line" microcontrollers that

The TSSOP package and 003 in the part number suggest that these chips are meant to be a drop-in replacement for the STM8S003 "value line" microcontrollers that used to be popular in China due to their $0.20 price point. At some point (many years ago, well before the pandemic and subsequent chip shortage) STM8s were hit by a massive price hike, which led to them disappearing almost entirely from cheap Chinese electronics. Several companies developed pin-compatible alternatives, usually based on the ancient MCS-51 architecture; the ones from Nuvoton seem to be particularly common, with one of them even being in charge of driving RGB LEDs on my desktop's motherboard. Here WCH seems to be particularly late to the party, but this RISC-V chip might finally start killing off the 8051 clones for good. It might even cannibalize WCH's own MCS-51 offerings, ironically.