How can I disable collecting changes in TeamCity for certain builds?

Question

Continuous Integration

Teamcity, Git with bitbucket.
Several versions of the product are being developed
in parallel. Team City has a separate sprint build, in which all mergers are built in different branches, and successful builds are marked with a tag, which is then used in package build.
Package build additionally prepares and uploads a deploy package, but it builds according to the specified tag, without specifying a branch.
The problem is that TeamCity's first step is collecting changes, which is fast in a sprint build and can take hours in a package build.
I suspect that this happens because there is no normal dependency between tags - in a sprint build, the dependency looks within the branch, where changes go from the last commit to the future, and in a package build, one build by tag can be from one branch, the next build from another branch, and the calculation of changes between these two builds is basically incorrect.
Actually questions:
1. Whether correctly I guess an essence of a problem?
2. Are there options to disable collecting changes? - unfortunately I didn't find it in the documentation
3. Any other ideas?
ps Unfortunately, there is no access to the logs of the teamcity itself and its administrative settings. By rights, I can only create my own new configuration builds and VCS root. Agents, with a shell.