Tangentially, the UK government digital service (and made available to the wider civil service) uses the free tier version of Slack which retains but disallows access to historic messages.

FOI in this case (in lieu of anybody coughing up the licences) relies on regular manual exports and their secure archiving.

This isn't afaik an attempt to avoid accountability (in fact it's the opposite), just a good faith use of free software to enable cross department communication in the absence of a service from a high level mandated corporate partner.

https://www.computerweekly.com/news/450423927/ICO-highlights...