From the introduction of the Trial Chambers in 23w45a until 24w14a, the tree located in the entrance room (minecraft:trial_chambers/corridor/entrance_1) resembled a naturally grown oak tree.

In 1.20.5 Pre-Release 1, this tree was altered, as can be seen in the attached comparison. Since the changelog for this version does not mention any changes to the entrance room, it is to be assumed that the alteration was unintentional. This is further supported by MC-271137, which suggests that the tree was rebuilt dilettantishly between these two versions.

How to reproduce:

1. Create a world with the experimental toggle update_1_21 enabled.
2. Locate the entrance room of a Trial Chambers structure. Alternatively, the room can be placed using the following command:

   /place template minecraft:trial_chambers/corridor/entrance_1
   

3. Observe the appearance of the tree located within the entrance room.

Expected behavior:

The tree in the entrance room of the Trial Chambers would resemble a naturally grown oak tree, similar to how it was the case between 23w45a and 24w14a. 

Observed behavior:

The appearance of the tree in question differs from that of a naturally grown oak tree.

Further notes:

This issue was discovered while testing MC-271137. It can be considered an amendment to that issue. If 1.20.5 Pre-Release 1 were marked as affected in both issues for additional clarity, it would be appreciated.