Relief u/s 89(1) available under New Tax Regime ?

Hi 

Pls help me on the following 

1. Is Section 89(1) relief for salary arrear avaiable under new tax regime ?
2. Arear relates to FY 2022- 2023 and ITR for that year was filed under old regime.  Current year I opt for new regime. So calculation of relief should be based on old regime only, right ?