“Multicloud” means that you use multiple public cloud providers, such as Google and Amazon Web Services, AWS and Microsoft, or all three—you get the idea. Although this seems to provide the best flexibility, there are trade-offs to consider.
The drawbacks I see at enterprise clients relate to added complexity. Dealing with multiple cloud providers does give you a choice of storage and compute solutions, but you must still deal with two or more clouds, two or more companies, two or more security systems … basically, two or more ways of doing anything. It quickly can get confusing.
