When defining TrieNode objects in python, the overhead of using them results in a TLE. However, the same solution using dicts fits the time limit. Since using classes/objects better fits the OOP design principles, it is probably more desirable in an interview setting. Because of that I believe the time limit should be increased so that the users don't have to resort to using dicts to get the solution accepted. To reproduce the error please see the code in this post:
https://leetcode.com/problems/stream-of-characters/discuss/807637/Python-weird-TLE-when-using-TrieNode-objects-vs-dict