Why does this happen?

several opponents starting yesterday can summon tons of units and cast multiple spells, probably around three times before my skills go off cool down after using it the first time.

I noticed this and then I exited the game, clearing background activities on my phone suspecting if this is a bug. But when I started the game I won the match!? WTF is this!? This is stupid. Is this a cheat or is this a bug?

see the screenshot. around 6 mana I won the match, take note that I just restarted the game and I have no damage on my portal. I closed the game around 10 seconds after the game starts because this particular opponent summoned two vipers and an executioner (I forgot to take a screenshot of the start of the match) so I knew there was something wrong.