No problem, you can store any type inside a list unlike in the “olden days” when other languages had arrays that only wanted one type of data stored in them.
Since lists can also store other list, and other compound data structures, along with other object references, processing or iterating through the list may become a bit more complex due to possible multiple layers, than just going through an array in a simple single level iteration. This is also related to shallow and deep copying.
If the code processing the lists is aware of this, I can’t think of any problems due to this ability to store different things in a list.