Workflows are triggered by the events which set in workflow yml under on keyword. If you use GitHub API to create a deployment, then all workflows with on: deployment will be triggered. Github Actions doesn’t support to specify a workflow name when event happens.
>> I’m trying to replace the current CI that we’re using and create an app for manually triggering specific workflows.
If you don’t want to trigger a workflow when you create a deployment, you need to remove on: deployment event from your workflow yml.
There are all supported Events that trigger workflows: https://help.github.com/en/actions/automating-your-workflow-with-github-actions/events-that-trigger-workflows
Also, you can show an example for your scenario, then let me see whether I can find a work around .