Steps to replicate the issue (include links if applicable):

• Note validation errors related to the performer.active_browsing_session_token contextual attribute:

https://logstash.wikimedia.org/goto/c12359f4ce94c4469dd5a00678afa40a

What happens?:

product_metrics.web_base stream shows the following related error:

'.performer.active_browsing_session_token' should NOT be shorter than 20 characters, '.performer.active_browsing_session_token' should match pattern "^[0-9a-z]{20}$"

What should have happened instead?:

'.performer.active_browsing_session_token' should validate

Other information (browser name/version, screenshots, etc.):

This seems to coincide with a sudden drop off of events produced:
https://grafana.wikimedia.org/goto/3gZ5qaQHR?orgId=1

{F65698613}