Try using flowDefinition

/services/data/v57.0/tooling/sobjects/flowDefinition/3006F0000005wMkQAI

PATCH:

{ 
"Metadata": { "activeVersionNumber" : "1" }
 }

Try using flowDefinition

/services/data/v57.0/tooling/sobjects/flowDefinition/3006F0000005wMkQAI

PATCH:

{ 
"Metadata": { "activeVersionNumber" : "1" }
 }

To deactivate, set activeVersionNumber to 0.

Note: While FlowDefinition's tooling API access is partially deprecated, you can still use it for Activate/Deactivate operations. If you are updating the entire metadata(along with Active status), you can use Flow with Active flag flipped on. If not, FlowDefinition is the API that you need to use.