Specifically, can I use the youtube logo on my website as a button to link to a video on youtube that I made?
What if I trace the logo, and/or change it a little to fit with the general theme of the website, e.g. crop it to a square shape? Or if I trace the logo badly, and it ends up similar, but not 100% the same (e.g., the gradient is slightly off)?
Should I declare anything specific on my website?
What if I use e.g. the Apple Logo to link to Apple Music (which has a different Logo)?
And the last, maybe most important question: What if I do it anyway? Can I expect a takedown request, a full-on lawsuit, or nothing at all?
P.S.: I'm based in austria, but please still answer the question if you're only knowledgable in other countries' law systems, since I think this may also be helpful for other people.