To make the process of deploying Growth features easier, we are consolidating how the welcome survey links to our data retention policies via T252572: Scale: update survey privacy link. The policy that we'll link to is the one that applies to Growth team EventLogging data, which can be kept for 270 days. Right now, the welcome survey data (as governed by the legacy survey privacy statement) can be kept for one year. In T208369: Welcome survey: anonymize data after one year, we implemented this policy.
With this task, we want to shorten our window to 270 days, but do the same activity in terms of aggregation and deletion. This should not affect what data we aggregate -- just that we need to make sure to aggregate and delete it sooner in its existence. This work will probably be done by @Tgr and @nettrom_WMF.