It appears that there’s been a recent change which applies auto-pause to kayaking, but I suspect it uses cycling parameters, which are not appropriate for kayaks (which move more slowly than bikes). I record my kayaking outings on my iPhone. In my most recent kayak outings, Strava auto-pauses almost immediately and then never unpauses. I’ve used Strava for years and this never happened until now.
My settings: I have auto pause enabled for cycling, but turned off for running. There doesn’t seem to be a way to control auto-pause for other sports.