I'm non resident with financial investments in France

You are liable for tax on everything you earn in France that is taxable in France under international tax treaties.

Financial investments are liable for direct debit by your bank. Depending on the type of investment, they may be exempt.

You are liable for tax on income earned in France, and for local taxes (property tax, residence tax, etc.).
As a non-resident of France, using the online payment system via your personal account ensures that your payment will be directed to the correct tax department.
Your income tax is calculated using the progressive income tax scale and factoring in income splitting (quotient familial). For any income earned after your departure, you will be taxed at a minimum rate of 20%.