Definitely. Wifi and BT are in the same frequency band, so there is always some sort of interference. There are quite e few reports on bad video quality with the stock app and Gamesir connected via BT.
aTello (written by Krag) can be found here, along with detailed instructions: Android testers needed.
0.92 is the current version. Imho, it works a lot better than the stock app. There is virtually no lag in the controls and in the FPV video.