IPad iOS 12,1 Playing on version 4.2 of gems.
I just played a solid 20 matches of ranked pvp, where all the opponents were the starter battle troops from the Primal Rift.
Regardless of which of the three opponents I picked every battle was the deck from the current faction event. I moved from tier 14 to 4 without leaving the pvp menu in every battle this was the case. When I hit tier four I went into the highest ranked opponent and all the sudden there troops were normal.
The images for opponents troops were normal in the selection screen.
The images for the listing screen varied with the Primal Rift characters and the opponents opponents actual troop.
The ascension and Stat levels varied per battle.
The rewards from the battle were normal for which opponent I picked.
Before I had started playing pvp I had completed Two floors of the current faction event. The level thirty floor and forty floor. I did not lose troops in the battle and was out of sigils to continue. I collected my reward and began playing pvp the bug began. After reaching tier four I had not entered any other menu besides battling when it returned to normal. Once leaving the pvp menu everything was still good as well as restarting the game.