I revamped four of my houseplants yesterday. Actually got rid of two of them as they were not giving me joy and I changed the pots and substrate for the two chinese evergreens that I wanted to keep, one was a bit puny so was never sure about that but on removing from the pot, I could see the reason. Some of its roots were rotten from being too wet, the other plant was in good condition but needed a bigger pot. They are now temporarily in my utility room and are already starting to look bright
Plants can become floppy from overwatering. They can get brown leaves from being too dry or if the sun burns them, leaf drop if not happy. Before getting rid, gently slide out of their pots and have a good look at the roots, you may well find the cause there. I would re-pot after that and probably cut the plants down quite a bit, so they still look nice. This is the time of year to very much reduce watering, so mine have had their last watering last week and definitely no baby bio for a few weeks now