Not necessarily. Self-hosted services are protected by company firewall / VPN. They can setup very restrictive network access. They don't have the same level of risks as public services like GitHub or GitLab.
Establishing an entry point via VPN is Lapsus$ primary first step.
Self-hosting always increases the operational burden of making sure your systems are secure. Maybe you have the engineering resources to spend on patching everything immediately and conducting in-house pen tests, but for most companies it's much, much more secure to let the software's developers host it as well.