I had a similar problem with the battery on my 2011 Toyota Sienna. I didn’t have a starting problem, because I keep an eye on things under the hood. At any rate, I cleaned the terminal, bought the impregnated rings that go under the battery clamp along with some anti-corrosion spray. I found myself cleaning the terminals about every three months. The last time I was going to clean the terminals, I found that about half of the positive clamp was eaten away. I didn’t have time to do anything, so I took the Sienna to my independent shop. They told me that the clamp was made of steel instead of lead and replaced in with a lead terminal clamp. They also said the battery was marginal under a load test, so I had them replace the battery as well. The problem is called “out gassing” where the sulfur dioxide fumes leak around the terminal. The Toyota service manager admitted to me that they had seen a lot of these problems with the batteries that came in some of the Toyotas My particular battery was made by Johnson Controls, but any battery can have this problem.
Years ago, my trusted Sunoco service station would clean the battery terminals, if needed, every time I brought the car in for servicing. I was living in an apartment at the time and had no place to do my own oil changes. I was never charged for this service. When I did my own servicing, I always checked the terminals. Today, this service of cleaning the terminals is often overlooked.