I have a 29 gallon in my office with a bunch of buce and crypts. It's home to a dozen neocaridinas, a dozen green neon tetras, and a pair of apisto agassizii. There are a couple tiny java ferns and a bit of moss as well. I use CO2 on a timer. Everything has been copacetic for about 6 months or so.
I did an 80% water change last week, and stuck a few more buce/crypts and some dwarf hairgrass in there. The pH came down a bit as expected, and the water turned a bit cloudy, what looked like a bacterial bloom. I left for the weekend, and when I got back to work all of the new buce was almost gone, all of the crypts, new and old had melted, and even my old well-established buce looks like it's disintegrating. All of the shrimp and fish look fine. Also... the java fern, hairgrass, and moss look totally normal.
I fertilized a touch after the change, but I'm at Nitrates 20, Nitrites 0, Hardness 75, Buffer around 100, pH 7, no chlorine.
Did I get some round-up in my tank? Not sure how I would, but there is some sitting outside my building near the hose that I use to fill my water bottles and I always give it a side-eye when I go out there. Because my non-dicot plants are fine, I'm really suspicious of glyphosphate. Also just super-sad about the devastation of my plants that I loved so much.
If somehow I did poison my tank, I'm terrified. I know that bottle of round-up is out there, but I never touched it at all! I think I can never use that hose again anyway.