The models tended to overshoot the number of deaths by huge amounts. For example, the Imperial College of London estimated 40m deaths in 2020 instead of the 2m that occurred.
The model authors have since argued that the data was correct, but people responded to the pandemic by changing the way we live. That's OP point: that feedback cycles and corrections exist and they make modeling dynamic systems very difficult.
https://www.wsws.org/en/articles/2020/03/18/covi-m18.html
https://www.nature.com/articles/d41586-020-01003-6
https://www.imperial.ac.uk/news/196496/coronavirus-pandemic-...
The model authors have since argued that the data was correct, but people responded to the pandemic by changing the way we live. That's OP point: that feedback cycles and corrections exist and they make modeling dynamic systems very difficult.