Is your silicone pure or a fake blend?
This came up a few years ago and I keep seeing references to the cheat blends. Not being an alarmist but I agree about the differences.
I avoided for years. Then a friend gifted a collapsible funnel years ago. Love it but it is not for cooking. I picked up another that is crappy and does not hold the 'collapsing'. Even stained just from filling spice blend containers.