I find risk slightly bigger when you encrypt your private data with the product of the company and store that encrypted data on servers of the same company.
Why: because if they have some backdoor now or plans to introduce it in future, they have all the time in the world to apply that backdoor to your data. Without you knowing it.
Keepass could have backdoors too. The difference is: authors of those backdoors are not from the same company, which I use as cloud storage.