See What is a Sandbagger? in the Help Center:
"Sandbagging falls under the broader category of rating manipulation, which includes activities such as:
- Arranging game results intentionally.
- Playing with multiple accounts.
- Choosing the wrong skill level on a new account.
- Losing intentionally to lower one's rating."
If I understand this correctly, gaining playing strength elsewhere is not sandbagging. But I admit I don't know the details of the detection system; you should read the entire help page.
See also Sandbagging detection system from November 2025.
I haven't played against humans for the last 6-7 months. But I HAVE been playing against bots. So if technically I get WAY better just by playing bots and then go back to playing humans on chess.com, will that be considered sandbagging by chess.com (and will they ban/lock my account)? Don't want to violate any policy and hence checking. If indeed this is sandbagging, what is the alternative to get back to playing humans?
I'm assuming the same applies to people who take a break from online chess but play OTB and get stronger and then suddenly return to online chess.