Prometheus cardinality stats queries:
sum(scrape_series_added) by (job)
sum(scrape_samples_scraped) by (job)
prometheus_tsdb_symbol_table_size_bytes
Doc:
scrape_series_added{job="<job-name>", instance="<instance-id>"}: the approximate number of new series in this scrape.
scrape_samples_scraped{job="<job-name>", instance="<instance-id>"}: the number of samples the target exposed.
prometheus_tsdb_symbol_table_size_bytes (gauge): Size of symbol table on disk (in bytes)
Symbol table: https://github.com/prometheus/prometheus/blob/main/tsdb/docs/format/index.md#symbol-table