A numeric filter never matches because the property is a string

• `filter: ['>=', ['get', 'pop'], 10000]` yields 0 rendered features with no console error
• `typeof f.properties.pop` is `"string"` with a value like `"12000"`
• Clearing the filter with `map.setFilter('districts', null)` makes the features appear

1. Print `typeof` of the property on a feature from `querySourceFeatures`
2. Remove the filter to confirm it is filtering rather than styling
3. Wrap the value in `['to-number', ['get', 'pop']]` and retest
4. Check how the source was produced, since CSV-to-GeoJSON usually keeps strings
5. Compare the filter literal type with the actual property type

Convert explicitly in the expression: `filter: ['>=', ['to-number', ['get', 'pop'], 0], 10000]`, and quote string comparisons (`['==', ['get', 'level'], '2']`); also coerce numeric fields to `Number` at ingest.

filter: ['>=', ['get', 'pop'], 10000]

const f = map.querySourceFeatures('districts')[0];
console.log(f.properties.pop, typeof f.properties.pop);
// "12000" string
map.setFilter('districts', null);   // 要素出现 -> 过滤条件有问题

• Quoting the threshold instead of converting the value (`['>=', ['get', 'pop'], '10000']`), which compares strings lexicographically
• Assuming the absence of a console error means the filter is valid, when a type mismatch silently evaluates to false