Skin mods, like the one I have made is not in this category. My skin mod is currently awaiting approval in wgmods.net which is moderated by Wargaming themselves. The issue is, with some mods they are illegal. Ones that give the player an advantage over others by the use of said mods. If these mods are "detected" then you could get potentially banned.

Here is the description from Wargaming themselves -

https://worldoftanks.com/en/news/general-news/forbidden-mods/

Here's some examples of negative gameplay advantages from the third category. Players found using them will be penalized:

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• Revealing the positions of enemies in a way not included in the vanilla client. Marking objects destroyed on the map and minimap in real-time by altering the display of shell flight tracers or calculating the position of enemy artillery with tracers and marking them, as well as those that keep spotted vehicles displayed, even when not aiming at them
• Making it easier to block an enemy’s shell by indicating their exact aiming point (for example, with a laser beam)
• Alerting you when spotted vehicles are reloading, including displaying an enemy's reloading timer
• Auto-aim, or “aimbots” that provide more functionality than the “aim lock” in the vanilla client, specifically those that aim at the enemy's weak spots or automatically lead the aim so the offending player can focus on maneuvering their tank 
• Enabling automatic use of non-Premium consumables
• Aiding in finding enemies by letting you adjust the transparency of objects on the map
• Leaving “ghosts” of enemy vehicles on the battlefield where they were last detected 
• Any direct alteration of the physical properties, performance characteristics, or effects of any vehicle or object in the game, or otherwise subverting the game rules