There are a bunch of obsolete GC flags from JDK 20 and 21 that might now be okay to obsolete/expire in JDK 23 and remove them as necessary.

The current suggestion is to obsolete all GC flags that are only deprecated now (MaxGCMinorPauseMillis, MaxRAMFraction,MinRAMFraction, InitialRAMFraction , DefaultMaxRAMFraction, TLABStats) in 23, and set them to expire in 24. All of these flags have been set to deprecated since <= JDK 13.
    all obsolete flags (G1ConcRefinement*, G1UseAdaptiveConcRefinement, G1ConcRS*, RefDiscoveryPolicy) should be set to expire in 23. All of these flags have been set to obsolete since JDK 21.

I do not see a reason to keep these around for much longer (particularly the deprecated-only flags have been deprecated for at least 4 years at the time when they are removed). Which means that in 24 and 25 we could drop lots of entries for this table...