Hello Marjan,
taking a look at the website, I could not notice any noticeably blurry images.
Could you provide some examples to clarify how they were displayed before compared to now?
Thank you.

Thank you for the quick response.

It appears sharp in the editor, but becomes blurry in the preview and after export.

The header PNG has always appeared sharp both online and in the preview until now.

All other images also appear blurry. They have always been displayed sharply until now.

For example, the photos of the people shown here are also blurry in the preview and after export, even though they used to appear sharp.Über die Schwimmabteilung - Schwimmabteilung des Ahrensburger TSV

Hello,
I was checking the photographs, rather than the logo.
At the default zoom level, no blurriness can be detected, although when increasing the zoom in the browser they become less nitid, and this can be noticed especially with the logo, but it is normal for this to occur.
For images used for this purpose, I would recommend considering a .svg image instead of a .png or .jpg one, as vector image maintain their quality regardless of zoom.
Do you perhaps have a recent backup of the project prior to adding this gallery so that the image quality could be compared between the previous version and the current one?

Online translation:

Hallo,
ich habe die Fotografien überprüft, nicht das Logo.
Bei der normalen Standard-Zoomstufe ist keine Unschärfe erkennbar. Wenn jedoch der Zoom im Browser erhöht wird, wirken die Bilder weniger scharf. Dies fällt insbesondere beim Logo auf, ist aber ein normales Verhalten.
Für Bilder, die zu diesem Zweck verwendet werden, würde ich empfehlen, nach Möglichkeit ein .svg-Bild anstelle eines .png- oder .jpg-Bildes zu verwenden, da Vektorgrafiken ihre Qualität unabhängig von der Zoomstufe beibehalten.
Haben Sie vielleicht ein aktuelles Backup des Projekts aus der Zeit vor dem Hinzufügen dieser Galerie, sodass die Bildqualität zwischen der vorherigen und der aktuellen Version verglichen werden kann?
Ich stehe Ihnen weiterhin gerne zur Verfügung.

I have been working with Website X5 in its various versions for almost 15 years, and I have never encountered this issue before.

 have already tried to find a solution with ChatGPT, but unfortunately without success. Since I have never encountered this issue before, I am wondering whether a setting may have been changed unintentionally when the gallery was added.

The uploaded images have always been sharp, whether they were JPG or PNG files. Using different versions of Website X5 and working on numerous projects, I have never encountered a problem like this before.

Could there be any global settings that may have changed when I added the gallery? Are there any settings that could cause images to be heavily compressed?

Hello Marjan,
how is the image optimization set in Step 1 - Settings ---> SEO?

Adding a Gallery should not affect these settings, however.

Exactly like that...

Hello,
it is set to None?
Unfortunately, investigating this is difficult as checking your website does not show heavy compression or very noticeable blurring, unless you are using a high level of zoom in the browser settings
If that were the case, however, it would be unusual for the logo to be displayed nitidlyin the past, as it is not an .svg image.

As mentioned, do you perhaps have a past backup before you added this Gallery?

"Unscharf" liegt auch im Auge des Betrachters.

Die kleine Unschärfe dürfte durch die interne Umrechnung der Bildpixel kommen, wenn von einem großen Bild mit vielen Pixeln zu einem kleinen Bild mit weniger Pixeln umgerechnet wird.

Tipp: Bei Personen von einem kleinen Bild zu einem größeren Bild in der ShowBox verlinken, siehe

Meine Testseite >> https://findelinks.de/123test-aufklappmenue-2/foto-und-beschreibung-2.html

. . .

Noch eine Anmerkung zu "verlorenen Bildern":

Beim Anruf meiner Testseite musste ich feststellen, dass zwar die 4 kleinen Bilder zu sehen waren, aber beim Klick auf die Bilder wurden nur 2 große Bilder in der ShowBox angzeigt.

Der Grund war, dass das Objekt "Bildergalerie" 2 Bilder "verloren" hatte, siehe

----- Screenshots (1) vorher - hier fehlen 2 Bilder -----

----- Screenshots (2) nachher - fehlende Bilder hinzugefügt -----