“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.
For example, one client confused security systems and thus inadvertently left portions of its database open to attack. It’s like locking the back door of your house but leaving the front door wide open. In another case, storage was allocated on two clouds at once, when only one was needed. The client did not find out until a very large bill arrived at the end of the month.