If it’s pure sugar (a soda) I’d say 45grams it definitely an upper limit to never overshoot.
If it’s home cooked pasta 100g at lunch won’t do you any harm depending on what you serve it with.
Especially if you start avoiding all carbs at dinner, which is not a bad idea, having some carbs at lunch in the form of pasta or bread (but halving the dose) will keep your metabolism spinning.
Keep in mind I am Italian so when I say pasta or bread I am talking about prepared food so no macaroni and cheese or garlic bread (FWIW, as benchmark, do not eat at olive’s garden. If I have to indulge in junk food macdonalds better)