To be fair, members of Thanos and Cortex projects do contribute code to Prometheus, which might explain why they are named more often here.

To be fair, VictoriaMetrics also contributes to Prometheus ecosystem by providing open source cost-effective remote storage for Prometheus, which is easy to setup and operate.

Additional contributions to Prometheus ecosystem include:

* Filing issues and feature requests for Prometheus [1], [2], [3].

* Publishing introduction materials for Prometheus users [4], [5].

* Helping Prometheus users at prometheus-users Google group [6].

[1] https://github.com/prometheus/prometheus/issues/4456

[2] https://github.com/prometheus/prometheus/issues/4769

[3] https://github.com/prometheus/prometheus/issues/5166

[4] https://medium.com/@valyala/promql-tutorial-for-beginners-9a...

[5] https://medium.com/@valyala/prometheus-storage-technical-ter...

[6] https://groups.google.com/forum/#!searchin/prometheus-users/...

I explicitely said "code".

Thanos and Cortex use some code from prometheus. That can explain that. Try looking timescale or opentsdb in the issues/pr.