Same can be said about most cloud platforms that programmers would store their code. "What if Google Cloud shuts down", "What if service X changes their API", "What if your CI/CD provider makes a breaking change in their YAML syntax".
This happens, it sucks, but it's not a reason to not host on cloud, use an API, or deploy with a CI/CD. Outsourcing is a calculated risk.
The difference is that Integromat is less fungible than, say, GitHub. If GitHub were to shut down, I could move to GitLab or my own Gitea instance, and it would be a fairly easy adjustment (mostly just changing the domain name everywhere). If Integromat shuts down, you have to completely rebuild your workflow on a competitor's platform because they're not based on a common protocol.
This happens, it sucks, but it's not a reason to not host on cloud, use an API, or deploy with a CI/CD. Outsourcing is a calculated risk.