I believe this bug has been around for 20 years now. It was not a problem with IE but is currently a problem with Edge, Chrome, Firefox, and Safari. Even further, I understand it even came along with the codebase with the newer Power BI Server for the classic-style paginated reports. These are reports created with the Power BI Report Builder. I believe these reports also use an RDL-derived language.
It's a bug with the Line control. The Line control will display broken images before and after the line unless an InterationID is tacked onto the end of the URL, like this:
&IterationId=0
A report dev could switch out the used Line for a different control and add a border to one side to simulate a line.
Check out the article AND the comments here:
https://obscureproblemsandgotchas.com/uncategorized/ssrs-report-viewer-control-broken-image/
Good luck.