1st gen was roughly the 40s and early 50s.
2nd gen roughly the late 50s to the 60s
3rd gen from 60s to the 70s
4th gen was the 80s until late 90s and most has been upgraded to 4.5 gen and is operating since the early 00s.

The first 5th gen was produced in 97 and formally in service only in 2005. The F22 is only expected to be replaced as the premier USAF fighter by the F-47 in 2030.

That means 6th gen planes will be flying at least until 2055, which is when the first 7th gen planes start trials. And most likely later than that as each fighter jet generation has taken longer and longer to replace. Even the fifth- gen F35 is planned for operation until 2070. Malaysia being one or two gen behind is fine for a country our size.