ChatGPT says:
Elevated homocysteine levels can be caused by deficiencies in B12 and folate, but can also be caused by other factors such as genetics, kidney or liver dysfunction, and certain medications. It is possible that your B12 and folate levels are within the normal range, but that you may still have a deficiency in one of these nutrients. It is also possible that there is another underlying issue causing your elevated homocysteine levels. I would recommend consulting with a healthcare professional for further evaluation and to determine the best course of action.