According to the SAFe 6 Scrum Master documentation, one of the ways a Scrum Master/Team Coach can help improve ART performance is to facilitate cross-team collaboration. Cross-team collaboration is the ability of Agile teams to work together effectively and efficiently to deliver value to the customers and stakeholders. It involves sharing information, resolving dependencies, aligning on goals, and providing feedback. Cross-team collaboration is essential for achieving the ART vision and objectives, as well as for delivering integrated and high-quality solutions.
The Scrum Master/Team Coach plays a key role in facilitating cross-team collaboration by 1:
Participating in the Scrum of Scrums (SoS) and ART Sync meetings, where they communicate the team's progress, impediments, and dependencies, and coordinate with other teams and the Release Train Engineer (RTE) Helping the team prepare for and participate in the PI Planning event, where they collaborate with other teams to define and commit to the PI objectives and identify risks and dependencies Supporting the team in the System Demo, where they demonstrate the team's work to other teams and stakeholders, and receive feedback and validation Assisting the team in the Inspect and Adapt (I&A) event, where they review the ART performance, identify improvement opportunities, and create action plans Encouraging the team to adopt Communities of Practice (CoPs), where they share knowledge, best practices, and learnings with other teams and experts Promoting a culture of trust, respect, and cooperation among the team and other teams (Must be taken from SAFe 6 Scrum Master resources) Reference:
Scrum Master/Team Coach
Team Sync
PI Planning
System Demo
Inspect and Adapt
[Communities of Practice]

Explanation/Reference:
https://www.agilest.org/scaled-agile/scrum-of-scrums/