Environment

• TeXstudio: 4.0.4 (git n/a)
• Qt: 5.12.8, compiled with Qt 5.12.8 R
• OS: Linux (Pop OS 20.04 LTS)
• TeX distribution: miktex

Expected behavior

If the option "Fit to Text Width" is marked, the zoom of the viewer should always be in consonance with the text width.

Actual behavior

If text width changes, the zoom keeps the same. The only way to make it update is to close and reopen texstudio or to change the viewer mode (from embedded to windowed or viceversa).

How to reproduce

Make a new document and write only a word. Compile and view. Then add a paragraph. Compile and view. The zoom in the preview does not adapt to the new text width.
Another way to reproduce is to have two documents with different margins and change the view from one to the other.