When I insert a video, it gets stretched for viewing, even though the video is in a different format.

Hi ​@Penna clash 
Thanks for the report.

Please provide more information about the video and what you're seeing. Or check the link " How to Report a Problem," which provides steps to provide more information that can help us identify the issue. For instance,

• Which version of Premiere Pro are you using?
• What is the resolution of the video (for example, 1920×1080, 3840×2160, 1080×1920, etc.)?
• Is the video appearing stretched in the Program Monitor, the Source Monitor, or after export?
• Does the video itself become distorted, or is it only the preview display?

A screenshot showing the stretched image and your sequence settings would be very helpful.

Here to help
Ian

What are the media properties, sequence settings, and export settings?