It depends on what you are doing with Grafana but in most cases it is fine.
An example of when it might be a legal issue: if you are selling a product which contains Grafana with changed logos and still contains the Grafana name then you might be breaching the copyright.
The Grafana Word Mark is used in a manner consistent with this Trademark Policy and usage guidelines below;
- There is no commercial activity associated with the use of the Grafana Word Mark, including the requirement of third-party commercial software or services;
- The Grafana Word Mark is used only to refer to the Grafana project and/or technology
- The Grafana Word Mark is not used in an attention-getting or branding manner, or used as part of your product or service name;
- The Grafana Word Mark appears less prominent than your company or product name.
- The reference to Grafana does not create a sense of endorsement, sponsorship, or false association with Coding Instinct, the Grafana project, or the Grafana community.
You can read more here on the trademark for both the Grafana name and logo: