Depends on the nature of your startup, and if you have significant infrastructure/architrcture for your workload or not. If you have significant scale you likely have a DevOps / SysAdmin type.
Yeah, and if you're early, like a few-person startup, you hopefully have someone who can do ops things as needed.
When I was the one-person eng and ops departments for a few-person seed-stage startup, which already had a major customer in critical production... even when we bought SaaSes (e.g., GitLab), I still needed to spend significant time on the recurring manual steps of backup processes for everywhere we put data we couldn't afford to lose, even after I'd spent time to automate everything that was worthwhile to automate.
For my last side-startup, I just self-hosted Forgejo myself (Git, Issues & Boards, Wiki), and it's less work than when I was doing the same with paid GitLab SaaS.
It depends on the case-by-case circumstances, but sometimes self-hosting an open source package, on your laptop, random PC in the corner, or your existing AWS account, takes less of your valuable time than a paid SaaS does.
GitLab is more powerful in some ways, but early startups might want to look at Forgejo first.