> I mean an Iranian company using American products and expecting EU protection?! None of it makes any sense.

It should be noted that Slack has an office in Dublin so it very likely has an Irish subsidiary (just like Apple, Google, and half of the tech industry so they can avoid taxes) and thus is subject to EU requirements. The GDPR applies to them, and since they have an EU company they (I believe) need to obey GDPR requests from any source. [EDIT: This is incorrect.]

But I can understand why Slack would cancel their account, since violating export sanctions is a really easy way to end up in gaol.