Is Zakat obligatory on the amount of a Tawarruq loan that was invested in purchasing a car, paying off debts, lending to colleagues, contributing to real estate, and investing in the stock market, and how is Zakat calculated on borrowed debts and owned shares?

The debt you owe to the bank does not exempt you from Zakat. One should not borrow money to enter the stock market, especially if the loan is substantial. As for the money you lent to your colleagues, Zakat is obligatory on it if they acknowledge the debt and are solvent. You have the choice to pay its Zakat annually or after receiving it for all past years. If the debtor is insolvent or procrastinating, Zakat is not obligatory until you receive the money, then a new lunar year (hawl) for it begins. As for real estate contributions and shares intended for trade, they are considered trade goods, and their value must be assessed at the end of the year, and a quarter of a tenth (2.5%) of their value must be given as Zakat.