Which FY did the NEW tax regime start?

I am helping a senior citizen & a super senior citizen to file their taxes from FY 2020-21 to FY 2024-25. So basically for 5 years. Never filed a return before.

So 4 years will be ITR-U and last 1 year will be regular ITR.

They have no medical insurance, HRA, political donation, medical expenses etc. Basically no deduction.

No Capital Gains either. No investments like stocks, mutual funds etc.

Just FD interest, Savings Account Bank interest and just some old age pension (very little).

I am assuming the NEW tax regime will be better for them as opposed to OLD tax regime, as they don't really have any deductions to claim?

Income is around 10 Lacs per year.