The issue seems to be with the above line, when using OutboundLink with a target="_blank" prop, there are redirect checks in other parts of the code, but not here. If you would wrap line 38 in the same if statement as on line 42 it should fix the issue.
https://github.com/flpvsk/gatsby-plugin-gtag/blob/57653fd6cd65612a84712bf0e2127e04cc2b3e53/src/index.js#L37-L39
The issue seems to be with the above line, when using OutboundLink with a target="_blank" prop, there are redirect checks in other parts of the code, but not here. If you would wrap line 38 in the same if statement as on line 42 it should fix the issue.