Xbox Gamerscore

Here's my suggestion: Allow you to keep your gamerscore from the previous console, but keep it separate from the Xbox One. Basically, when viewing achievements, you can see your Xbox 360 achievements & your Xbox One achievements separately, although they
will still all go to the same gamerscore. This way, you can see at a glance what your gamerscore earned is for each invdividual console.

An example:

Total Gamerscore = 100 G

Xbox 360 Gamerscore = 75 G

Xbox One Gamerscore = 25 G

Gamerscore resets

A gamerscore correction occurs on a player’s Xbox Live account when they gain achievements through avoiding gameplay and using external tools. Xbox Live is committed to keeping the service free of this type of behavior as it violates the Xbox Live Terms
of Use. When abnormal achievement or gamerscore activity is found, Xbox Live modifies the gamerscore of players who meet specific and automated criteria.

An Xbox Live player who obtains their gamerscore in this abnormal way will:

Find their gamerscore reset to zero.

Be unable to regain all previously earned achievements.

Be labeled as a “cheater” for the community to view.

A Gamerscore correction occurs on a player’s Xbox Live account when they gain achievements through the use of external tools and avoiding gameplay. Xbox Live is committed to keeping the service free of this type of behavior as it violates the Microsoft Services
Agreement and Code of Conduct. When abnormal achievement or Gamerscore activity is found, Xbox Live modifies the Gamerscore of players who meet specific criteria

When a Gamerscore correction occurs the player’s Gamerscore is reset and previously-earned achievements remain unobtainable.

Gamerscore cheating will result in a reset of the account’s Gamerscore, and depending on the circumstances and severity of the violation may be accompanied by a temporary or permanent account suspension. Under certain circumstances, a Gamerscore correction
may be limited to achievements earned on a particular platform. Egregious or repeated Gamerscore violations may lead to a device ban.

No. The only way Xbox deletes gamerscore is by a gamerscore reset which is when they've found a person cheating and completely clears their gamerscore and labels them a cheater.

The gamerscore on Xbox.com may not reflect your most recent gamerscore on the Xbox 360. How long has it been since you received the gamerscore update on your console?