You can utilize the search with the advanced search operators (e.g @username) to look up cards assigned to a specific user.
If you are looking for cards that are assigned to you, open the My Cards Page at https://trello.com/your/cards. You can also replace the username (your in this example) in this link with any other member on your team to see the cards assigned to them.
However, we do not offer any specific reporting in Trello. You can however check out these 3rd party solutions that might help with that:
If you had to thrive a new habit during a lockdown, what would it be? Trello
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