With a growing subset of YouTube’s users becoming more aware of how the platform is monetized, YouTube appears to be paying greater attention to those with a preference to opt out, whether that’s through browser extensions like uBlock Origin or other methods that require even less effort.
That’s only if you agree to the developer TOS. Invidious doesn’t use the Developer API and as such never agreed to the associated TOS. This is against a terms of service that is not relevant to Invidious.
You have to agree to it in order to view YouTube. If the software doesn’t present those terms, it in itself is in violation.
#1 No, this is not in the end user’s terms. The Terms presented to end users only speak of advertisement in how they may be served to the user, and in how as a creator, users must abide by the Advertising on Youtube Policies
#2 It’s extremely questionable that their TOS is legally enforceable anyways as it doesn’t meet the legal threshold for a browsewrap agreement, i.e. an agreement made legally binding by a user’s continued use of a service. Browsewrap agreements require that the language and placement of the website’s terms are submitted to the user in the form of some sort of notice or notification. No such thing is required in order to use Youtube. Of course, this goes out the Window once you have an account, as then you’ve entered a clickwrap agreement with Google’s entire ecosystem, but before that, Youtube does not even attempt to enter a browsewrap agreement with users.