From my personal experience and understanding, the Infosys rehire policy is often misunderstood. It's true that Infosys has a strict rehire policy because once an employee resigns, it can be challenging to return. Typically, they have a “no rehire” policy, especially for those who leave voluntarily. Big companies frequently use this method, despite its clear brutality, to effectively handle employee resources. However, this doesn't mean that doors are permanently closed forever for every ex-employee. In exceptional cases, especially if someone has a rare skill set or a strong reason to return, Infosys might reconsider.
Regarding the idea, companies like TCS avoid hiring ex-Infosys employees, this feels more like a rumour. From my network and personal contacts, I haven't seen any solid proof suggesting that leaving Infosys negatively affects opportunities in other companies like TCS. In fact, many ex-Infosys employees switch to other companies within the industry without issue. The tech world is big, and companies generally value your experience rather than holding your previous employer against you.
Overall, while the Infosys rehire policy may feel strict, it doesn't impact your future job and opportunity in other companies. If you're considering a career change, your skills and experience will hold more weight than any rumour regarding rehire policies.