I noticed that mozorg attributed downloads never have a 'default' profile selection reason - see https://sql.telemetry.mozilla.org/queries/104298/source#256886 Maybe it helps understand the root cause?
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I noticed that OS pre-installs seem to be a particularly strong driver in "default" - see https://sql.telemetry.mozilla.org/queries/104298/source#256890 Maybe it helps understand the root cause?