https://smile.amazon.co.uk/gp/product/B07KZT8F6R/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Is it a capacitive or inductive method, or some thing else?

 

From a picture in the comments, it's a CAEA WS-02 water level sensor. A web search reveals this link. It's a capacitive sensor.

https://trumsense.com/products/ws02...-intelligent-touchless-liquid-level-sensor-92