When you use tactical view, there will be a blue arrow line extended from your ship in the direction of your ship is moving. That is easily understand.
But there blue line will also appear from accelerated gate or jump gate. Is it a bug?
The blue line should be a line between your ship and a targeted (or selected) item in space. This can be anything from a Stargate, Celestial, ship, drone large Collidable object etc.
So, in short, that looks like everything is working as intended. That being said, if you ever believe that you have found a bug, please file a bug report. Press F12. And click the bug report button.
One of our awesome bug hunters will take a look and see what they think.
Blue line/arrow always point in the direction of your ship and has length proportion to ship speed, so warping will make the the line extend all the way to the edge of your screen.
White line connect your ship with object you select.
In my picture, the upper blue line start from my ship, which is in the middle of the tactical view, go all the way to the right side. The line that connect my ship and the station is white. I believe these 2 lines work as intended and I have no question.
The lower blue line start from station going all the way to the right. This is the one I think is a bug. Why a stationary object has a speed line pointing in the same direction my ship is going?
Oh, my apologies, I completely missed the second slightly lower blue line. You may want to file a bug report. Alternatively you could move this post to the #issues-workarounds-localization forum section to see if anyone there is able to help.