See https://logstash.wikimedia.org/app/kibana#/dashboard/eventlogging
'findText' is a required property event_revision: 18115552 event_schema: MobileWikiAppFindInPage
raw_event
{"dt": "2020-01-08T17:11:28Z", "event": { … "userAgent": { "browser_family": "Android", "browser_major": "7", "browser_minor": "0", "device_family": "Phone", "is_bot": false, "is_mediawiki": false, "os_family": "Android", "os_major": "7", "os_minor": "0", "wmf_app_version": "2.7.50302-beta-2019-11-08"}, … , "wiki": "enwiki"}
Impact
I believe these events are currently silently discarded and not added to the database due to being invalid according to the schema.