I clean mine with these:

M3 Naturals Retainer and Denture Cleaner 120 Tablets Removes Bad Odors Discoloration Stains Plaque for Cleaning Invisalign Mouth Guard Night Guard and Removable Dental Appliances https://www.amazon.com/dp/B075WWYBJ7/ref=cm_sw_r_apan_i_RY6TJVNPH3XMVB9CG2D9?_encoding=UTF8&psc=1

nope, never. after the cleaning cycle, they come out looking brand new. I use tablets that I get on amazon, a half tablet each time. works perfectly

https://www.amazon.com/dp/B075WWYBJ7

another tip I can share is never let the trays dry out. I’m either wearing them, or they’re stored in water in a little watertight container

I use these, but I think anything similar should work fine https://www.amazon.com/dp/B075WWYBJ7