See here https://www.elastic.co/guide/en/elasticsearch/guide/current/random-scoring.html
This has come up in the past on SO by other users as well.
Thank you for your feedback. While it is unlikely we’ll address this suggestion in the near future, we’ll reassess based on the number of votes it receives. The workaround mentioned here is very cool, by the way!
Azure Search Product Team
Yoad Snapir commented
I have ended up working around this with the following technique https://medium.com/@yoad/pseudo-random-sorting-with-azure-search-28966ad851ae