We're sorry about the trouble with Photoshop. Would you mind telling us the macOS version you're working on? It would be helpful if you could share a screenshot showing the issue & if you could share more info. Please try updating Photoshop to 23.2 (if you haven't already) to check if it helps.
Thank you for your reaction and helpfullness. As English is not my native language, I hope you’ll understand my answer.
I had already updated to the latest version of Photoshop and by doing so Photoshop apparently went into the full screen mode. Embarrassingly enough, I didn’t notice, as Photoshop didn’t appear full screen on my computer. When a few days ago I accidentally touched the full screen button, the screen stayed te same, but the scroll bars re-appeared suddenly.