Using abi.encodePacked() with multiple variable length arguments can, in certain situations, lead to a hash collision. Since abi.encodePacked() packs all elements in order regardless of whether they're part of an array, you can move elements between arrays and, so long as all elements are in the same order, it will return the same encoding. In a signature verification situation, an attacker could exploit this by modifying the position of elements in a previous function call to effectively bypass authorization.
When using abi.encodePacked(), it's crucial to ensure that a matching signature cannot be achieved using different
parameters. To do so, either do not allow users access to parameters used in abi.encodePacked(), or use fixed length arrays. Alternatively, you can simply use abi.encode() instead.
It is also recommended that you use replay protection (see SWC-121), although an attacker can still bypass this by front-running.