Change the "Composite in Linear Color" setting for creating a new sequence to OFF by default.

Re: pre-multiplied -- thank you for your comment. I'm very familiar with what you're referring to. But that doesn't seem to be the problem. This issue will occur with a PNG file created with Photoshop that has less than 100% opacity. (Btw if you're doing a test, make sure to have a video layer or black video under the transparent graphic in order to see it. Putting the file in an empty timeline won't have the issue.)

That sounds like tge Alpha channel isn't matching Premiere's expected option.

Alpha can be either pre-multiplied or not. One works in Premiere, tge other doesn't. 

Dear Adobe, Please change the Premiere sequence setting default for "Composite in Linear Color" to OFF. Graphics with transparent alphas do not appear as intended when the default setting is clicked ON. Also transitions such as dissolves or fades to black do not look smooth. Thank you!