Firefox

it makes sense for its changelog to be shown alongside the rest of the OS update

I disagree. I primarily use Linux, and I get no such pop-ups when I run updates, but I do get a pop-up when I open the application in question. I do get notifications if there are important notices from packages though, like is there a configuration change to a system service.

There's no reason for me to know what changes Safari has until I launch Safari. So it's just an ad if it pops up at some other time.

How is that fair competition?

How is it unfair? If it's just an ad, there's no pressure there.

I draw the line at ads that put down competitors. I remember seeing Edge ads claiming Firefox was slow or insecure (forget which) within Windows. That's not a regular ad (e.g. use Edge, it's fast and secure), but active spreading of misinformation by a trusted source.

If Google did the same, I could totally see an angry anti-trust suit. But as far as I know, it's pretty much just "use Chrome for a more integrated experience" or whatever.

Correct me if I'm wrong though, I haven't used Google search in many years so I haven't seen their ads.

in the EU

Ah, okay. I'm in the US and am not familiar with EU law. I'm also not a lawyer, but this Wikipedia article on antitrust sums up my understanding pretty well:

First, the alleged monopolist must possess sufficient power in an accurately defined market for its products or services. Second, the monopolist must have used its power in a prohibited way. The categories of prohibited conduct are not closed, and are contested in theory. Historically they have been held to include exclusive dealing, price discrimination, refusing to supply an essential facility, product tying and predatory pricing.

The closest is "product tying," but there's no requirement to use Chrome to use Google search or any of Google's other products, and the opposite is also not true (you can select a different search engine, for example).

I'm no fan of Google, and I try to avoid their products where I can, but I haven't seen evidence that they're in violation of antitrust law WRT their advertisements for Chrome. I think they're in violation for making competing browsers work more slowly on their services though, but that's a separate thing.

Warranty void if removed stickers aren't legal, yet pretty much all devices have them, for example.

I'm pretty sure those are only explicitly illegal in the US, though they're unenforceable in most reasonable jurisdictions.

Regardless, point taken. If you're familiar with the provision you think Google is in violation of that isn't being enforced (whether in the US or the EU), I'm very interested. I would like to see Google broken up, but I'm not sure on what grounds that might be.