Reacting to stimuli ≠ feeling pain. Plants do not have a nervous system, nor a brain, nor any way of consciously feeling that pain.
If you want to understand what feeling pain is, feel free to watch farmers smash piglets heads into concrete (thumping, an industry standard) until they’re no longer breathing or pigs being dropped into CO_2 chambers and having every mucas lining in their sinuses, eyes, throats, etc acidified as they suffocate to death.
For me it was thumping, the industry standard way of killing piglets by grabbing them by the back of the head and smashing them into concrete until they’re dead. That or the CO_2 acidifying every mucus lining in a pig’s body, chemically burning them alive while they suffocate to death because people get enjoyment out of it