What is flagging in BTD6? (And how to prevent it)

This video I briefly go over what it means to be flagged for modding in btd6 and which mods to stay away from. Here are a list of the mods I used in this video to get flagged:
1. Infinite monkey money mod
2. Infinite monkey knowledge points mod
3. Infinite monkey tower xp and levels
4. All trophy store items unlocker
5. (unsure if this contributed to getting me flagged) NKHook6
6. (this one doesn't get you flagged but I used it in the video) BTD6 mod helper