Fine-tuned gpt-3.5 API returns different response when one symbol changed in input messages

OpenAI models have already been trained on millions and millions of training questions that are rated by tons of outsourced workers and then tuned with reinforcement learning.

You do not need to fine-tune gpt-3.5-turbo to be a customer support assistant, especially on grammatically awkward chat that has little to do with the user input and uses dumb placeholders that only train the model to output placeholders.