Please read my old response at the bottom of this thread.
According to Appodeal change log the last time they changed Vungle was:
2.6.0 (12 November, 2019)
- Chartboost updated to 7.5.0
- InMobi updated to 7.3.0
- IronSource updated to 6.9.1
- Mintegral updated to 9.13.5
- Ogury updated to 4.1.3
- UnityAds updated to 3.2.0
- Vungle updated to 6.4.11