Seems like it creates a conflict with the Enhancer for Youtube add-on which causes the video descriptions to be displayed twice, the second one being where chat comments or playlist would be otherwise.
There's an X button to close it but it's really unwanted.
Works pretty well otherwise

EDIT: Thanks for your answer. Might pretty well be, just thought I'd point it out because it only happens when both SponsorBlock and Enhancer are active.
Looking forwards to this being a thing of the past.
Regards