Didn’t want to post all of my many CSS snippets - there are far too many, most of them not activated. But I found Getting comfortable with Obsidian CSS. That helped to find the code in one of my CSS files.
/* with Sliding Panes plugin: title is written bottom up */
.view-header-title-container {
transform: rotate(360deg);
text-align: right;
margin-top: 10px;
}
Deactivated it, and title looks good again 
.