More of an unlikely exploit/vulnerability bug than anything, but does have game breaking potential.
The current name release policy of wow has changed from being released on character inactivity after 2 expansions to released on battle.net account activity after 2 expansions.
This means anyone can make a free wow account, use all 60 character slots of 1 wow account to take up names or variations and those wouldn’t unlock until minimum 4 years, potentially indefinitely.
However, even if they delete wow, as long as they use that battle.net account to play games even once within 2 wow expansions aka within those 4 years, like Hearthstone, or Heroes of the Storm (free games), or even play CoD, as long as they play from that battle.net account, that 4 years minimum on the names releasing becomes indefinitely.
Eventually, without changing the policy again to release names based on inactive characters or WoW account, or without adding last names, someone(s) could (with enough time on their hands) remove the ability for anyone to create any new characters (minimum 4 years or indefinitely) by depleting the entire remaining possible name and variant choices just taking names and words from dictionaries, 60 characters, 1 account after the other, 8 accounts per bnet account max, 480 names removed at a time, as many times as they wanted.
While not currently game breaking, and more on the “unlikely things to happen” spectrum, it does highlight the flaws in that the newest 2021 policy change regarding how the release of character names based on battle.net account activity instead of WoW or character activity is inadequate and needs revision.
EDIT
to reflect 60 characters max not 50 and clarification from This thread