Inherently by nature of existing no, but they can be easily implemented as such.

The censorship problems in the above are in the call to continue silencing/removals of political actors from discussion platforms and in pushing for centralized platforms to decide which political statements are factual. If you go an abstraction layer above that it gets too generic to universally claim as for censorship and if you go an abstraction layer below that it most often becomes an individual's choice.

Ad-blocking is turned off by default in most browsers.

Also basically no one wants to see ads, it is functionally useless, you can just go search for the thing you want to buy.

Censoring someone because you think they are harmful isn’t similar to this. You can develop a trump-blocker extension but having this enabled on default in a browser like chrome would be obvious censorship