Dark outline after rendering with transparent background

[Christina35401732p06o]

Hi. I've made an "write on" animation using thicc plug-in. I want to use it as an intro for my videos. After rendering and exporting file to another editing program (like capcut or davinchi resolve), a dark-gray outline appears. But if I import it into Premiere Pro, it seems to working fine. Are there any solutions to avoid this artefact outline? Thank you. 

[Rick Gerard]

When rendering with transparency, make sure you select Straight alpha instead of Pre-multiplied. Also, try increasing the bit depth and use ProRez 444 with alpha for the codec.