I generally start my research at the H&R Block website.

https://www.hrblock.com/tax-center/wp-content/uploads/2018/05/airbnb-taxes.pdf

(Inside joke)

But it's not that clear about "substantial services."  Most Airbnb rentals don't include daily cleaning (of course, many hotels aren't doing that either, these days).  But then, since the places are furnished, does that put it on Schedule C because of short-term rental of personal property?

Meanwhile, the TurboTax website is wishy-washy on this.  "When you rent out your home, make bookings and provide amenities, like coffee or breakfast, the IRS may treat you as being self-employed in the vacation rental business."  (Emphasis  added.)

https://turbotax.intuit.com/tax-tips/rental-property/10-tax-tips-for-airbnb-homeaway-vrbo-vacation-r...