Hmm, if the steamer is still steaming as normal with the same output, then nothing on that end should have changed, as of course that’s just steam from plain water. It may well just be the pads that are no longer as efficient at trapping the dirt and drying off the floors.
Only other thing I can think of has something been dropped on the floor and the steam just can’t cut through it? Something along the lines of something greasy (even something like fabric softener or mayonnaise - could be millions of things I suppose)? With you mentioning streaks, it may need a cleaning solution to cut through it the once and then the steamer used as normal.
