ANSWER:

You should make dua for them if they died on Islam!

It’s not permissible to talk bad about the deceased as we are witnesses of them on this earth!

Those people who we knew was tyrant but was Muslim and in same way some People from different sect who died as muslims but they carry a lot of wrong aqeedah which didn’t put them beyond the fold of islam,CAN WE MAKE DUA FOR THEM (as they died as Muslim)AFTER THEY DIED AND ALSO POINT OUT THE MISTAKES AND WRONG DONE BY THEM??