9 – Drupal 8 Content renders styles in body after each save

i am quite new to Drupal CMS and tyring to create a frontpage with different content-types. My problem is that, creating a new content or updating an existing content causes an error as you can see from the image below. Automatically styles are rendered in content and saved in db. It does not matter if i delete styles from content and save it, after each save it repeats the adding styles to content. I tried to search for the error but unfortunately could not find any similar problem and or any solution. Anybody does have any idea about the cause of the problem or how can i fix it?

Thanks for your help…

Drupal 9 Wrong Content body after Save