If you're on a committed plan and you have access to a sandbox application, this application will be on a separate sandbox plan, which has separate monthly usage quotas for Search Requests, Records and other usage.
As a result, sandbox usage doesn’t count towards your main plan's quota - and usage in your other applications application don’t count towards your sandbox's quota.
Additional Resources:
For Indexing Operations: How does Algolia count indexing operations?
For InstantSearch Operations: How does Algolia count InstantSearch operations?
For Refinement Operations: How does Algolia count refinement operations?
For Maximum Queries Per Second: How does Algolia calculate the Maximum QPS (Queries Per Second)?