Self-hosted open source logging stack

I need recommendations for an open source logging stack I can host myself to cut down on our current managed service costs.

We are looking to move away from our expensive managed logging service. What are some self-hosted, open source alternatives we can deploy ourselves?

We are looking to reduce our observability bills. Can you suggest self-hosted, open source alternatives for log management?

We are moving our logging infrastructure from a managed service to a self-hosted open source stack to save money.