Reproduction steps:
1. Open the attached project “BlenderImportBug“
2. Open “Assets/Scenes/SampleScene.unity“ Scene
3. Open “Assets/BlenderFile.blend“ in Blender
4. Drag “Assets/BlenderFile.blend“ into the Scene
5. Select “BlenderFile“ GameObject in the Hierarchy window
6. Observe the “Rotation“ of the Transform Component in the Inspector window and in Blender

Expected result: The “BlenderFile“ GameObject has the same “Rotation“ Transform in Unity and Blender
Actual result: The “BlenderFile“ GameObject Transform “Rotation“ property “X“ is “-89.98”

Reproducible with: 2020.3.43f1, 2021.3.16f1, 2022.2.2f1, 2023.1.0a24

Reproducible on: Windows 10

Note: Changing Transform Rotations in Blender and saving causes all rotations to change in Unity, but they do not match. If the Blender Prefab has a camera after deleting it in Blender and saving rotations of the GameObject in Unity are reset.

*{*}About the -89.98x rotation{*}*

This can be avoided by exporting the model as an .fbx and using the 'Apply Transform' option in Blender's FBX exporter.

Know that It does come with a warning about possibly affecting animations and armatures and is tagged experimental.