unfortunately, this is a well-known problem in the sim and has nothing todo with our data. This happens also with the NavBlue stock data. We had reported an equal issue to ASOBO with an example, in our case a STAR into EIDW but that happens on many, many STARs on different airports.
You can test it by your own - when you are on the worldmap and you select the ELTO2J STAR and let the approach part on automatic, it looks good and the a/c would follow the right path - you see also the correct waypoint sequence in the flightplan:
… but when you now, select ie. the ILS01L approach, you see the “strange” curve - and you see that the ARL-VOR was added in the flightplan:
The reason for that is simple - the ILS01L approach contains the ARL-transtion (for flight from north). This ARL-transition goes from ARL-VOR to D183E (= ARL183/5) and then in a race-track back to SA801 - FI01L (yellow marking):
The final-approach 01L goes from (blue marker):
SA801 - FI01L - RW01L
You see the SA801 is the connection point between the approach-transition and the final. The problem now is, that you can´t “de-select” the ARL-transition - nowhere and therefore this “strange” turn will always be added.
Sorry, this is currently a sim limitation and again, this could be happened on all STARs and IAPs, where you have at least one approach-transition, due the missing feature to select/de-select the possible approach-transition.
Hope that helps