Our home natural gas hot water tank did that. The semi-soft white “flakes” first showed up as a faucet flow restriction. They were revealed when I unscrewed the faucet end screens to investigate. Since they were in all faucet screens including the new washing machine’s, I initially asked our water dept. about it. They reported no such problem with their system, which narrowed it to our heater. Draining it exposed tons of the small white flakes.
Eventually the problem came down to a recall of the water heater some 8 years before due to deterioration of some internal component. Unfortunately the recall had expired and despite us never having been notified, the manufacturer refused our belated claim. I can’t recall the exact internal part, a liner, tube, or rod, but the material used was faulty. We still have the unit as it is larger than most and expensive, and the flaking isn’t nearly as bad as it initially was; screens and filters stop any flakes, and if I notice a reduction in flow I simply remove and backrinse the screen. The washer’s is a bit harder to get at and remove, but I routinely clean its two hose screens during annual washer/dryer service anyway.
I’d check the Suburban website for a recall, but if it’s 18 years old that’s unlikely to be fruitful beyond any insight it might provide. Beyond the anode rod disintegration, depending on composition the culprit might be the tank liner. A respected local plumber in our locale suspected the dip tube in our home water heater, and gave us a new flexible plastic one to replace it, which I’ve yet to do. If the dip tube has flaked away, it’s efficiency is shot and it’s my bad for procrastinating. Your Suburban I don’t think has a dip tube though.
After a bleach treatment in the coach, I always add, let stand, and flush baking soda to clear the system of bleach odor. But flaking has never been a consequence.
Ultimately your optimal fix may be a new unit. Sans a dip tube in your RV one, I still had to at least proffer up that the debris I had met your exact description to a tee.
Joel