In my unit it's just 365 days countdown. OTOH a lot of the Xiaomi purifiers have built-in air quality monitor so really you can just ignore the useless filter

In my unit it's just 365 days countdown. OTOH a lot of the Xiaomi purifiers have built-in air quality monitor so really you can just ignore the useless filter health value and figure out if the filter is working for yourself, based on how it performs.