Disable Slack logs?

Just got a response from Slack support on the same issue. She said:

Thanks for getting in touch, and I'm sorry for the concern generated with this logs issue — this is a known bug. It was caused by a Slack outage that we experienced a couple of weeks ago.

We'd never seen anything like this before and so I can only apologise that they suddenly started taking up so much space. We've got a bug report filed to improve on this in the future. I can let you know once we've implemented a fix if you like?

In the meantime, if you go to the menu and select Help > Reset App Data, you should see those files disappear. Please note, that this will sign you out of your workspace, so you'll need to log back in.

I just settled for manually deleting the log files for now, and will wait for the fix.