In the documentation https://cloud.google.com/bigquery/quotas it specifies that the 2,000 slots limit are per project:
Maximum concurrent slots per project for on-demand pricing — 2,000
We're experiencing this on the Organization level, i.e. the sum of slots used in multiple projects in the same Organization doesn't go above 2,000.
This doesn't isolate our dev and prod environments which is quite bad. Same goes for the number of concurrent queries.
Are there any undocumented limitations in BigQuery?