Playtime offerwall (adjoe)

Has anybody been noticing the recent changes on all websites/apps that have the offer wall playtime rewards? I swear that one day you were able to earn amount of coins per minute using playtime offerwall but now they changed it to x amount of coins per level or task completed. Any know if this is due to their anti fr@uD AI or just a recent update in general across all of their offerwall locations?