The Jupyter ecosystem got more complex in 2023. Want more background, see the second half of my answer here that references resources detailing how the Jupyter ecosystem changed a lot in 2023 with Jupyter Notebook 7+ now being built on the same components as JupyterLab.
The upshot of this is now it can be hard to tell what you are using for writing and running Jupyter notebook .ipynb files. However, knowing this can be important when you want to do something like display an interactive matplotlib-based plot or make a an animation.
KEY TIP: Older style has a 'Cell' menu along the File menubar.
Does the menubar the starts with 'File' include 'Cell'?