CSAT is typically calculated as positive ratings divided by all ratings received. With B2B accounts the number of responses is small, so look at individual low ratings and the account behind them rather than small swings in the percentage.
In shared Slack channels, keep the ask lightweight: one question after a request is resolved, in the same thread, and never more than once per request. Response rate matters as much as the score; if only unhappy customers answer, the number will mislead you.