Magic Carpet states you can't use "abilities" during summon and "any action" in flight cancels it, I would expect a channel to count as doing an action even though no input is required for it. You can combine Magic Carpet with Shadow Weave to invisibly fly basically anywhere, which is arguably ok for the cost but feels like an unintended interaction.
Also worth noting that this can be done with Mo & Krill's Burrow and Viscous' upgraded Goo Ball, as well as any other channeled ability that allows using items; those two are just particularly bad as they get around particular downsides of using them (no vertical movement and limited control respectively). Goo Ball is particularly bad as it deals contact damage.
Counting this as a bug since channeling an ability is arguably doing an action, which the carpet is supposed to forbid. Magic Carpet should cancel any channeled ability when used, since you can't start a channel whilst on it.
Also worth noting that this can be done with Mo & Krill's Burrow and Viscous' upgraded Goo Ball, as well as any other channeled ability that allows using items; those two are just particularly bad as they get around particular downsides of using them (no vertical movement and limited control respectively). Goo Ball is particularly bad as it deals contact damage.
Counting this as a bug since channeling an ability is arguably doing an action, which the carpet is supposed to forbid. Magic Carpet should cancel any channeled ability when used, since you can't start a channel whilst on it.
