Without any messaging telegraphing what's about to happen, this feels pretty dark pattern-y.
I'm a bit torn on this. On one hand, people expect to see a context menu when they right click, so being redirected is definitely jarring. On the other hand, if someone is right clicking their logo in the first place, they probably want to download the image for use in a design or something, so this can be seen as predicting user behaviour/ negative latency.
Its almost like the design equivalent to how some companies show dev job offers in webtools: https://elijahmanor.com/find-good-devs/
I don't agree at all that this is a dark pattern, tbh. It's not really a hidden user interaction designed to drive you towards a sale/conversion *(which is what I'd normally consider a dark pattern).
Obscure, unexpected, pretty strange user experience, perhaps. But I don't think it's fair to call it a dark pattern.