We stayed at Tesouro da Baixa by Shiadu in April/May 2022. It is a great boutique hotel located in a very centralized area of Lisbon that's within walking distance to many popular neighborhoods and sights (Tram 28 is right around the corner) in addition to the Rossio Metro stop (verde line) and train station to Sintra. Unassuming at first, the hotel entrance is tucked away in between the entrances of a shoe store; look for the big wooden door and blue sign.
Because it's so centralized, street noise can be loud at times, but we only noticed it if we had the window open. It never affected our sleeping. On the plus side, we had an amazing view that never got old over the 5 nights we were there.
The staff was so helpful and accommodating, and we enjoyed starting our day each morning with their impressive breakfast spread.
We would definitely stay here again, but if you're looking for something a little quieter, away from the hustle and bustle of the more "touristy" area of Lisbon, this might not be the best choice.