Is it offensive to leave comments on pull requests? Asking because short industry experience

I comment a lot because I work with juniors a lot. I go into details, examples, and how to refactor better. I love being commented on my PR's too because that way we keep a sharp eye out for each other, because we are team. Juniors level up faster with guidance, and I think in my experience, PR's are the way to go for efficient teaching.

Such was how I communicated with my juniors in my previous job, and in my current team in the new current job.

Then I had to do some edits on a different repo maintained by another team. I spotted some code that seemed fishy, and commented on it (PR made by a senior) ever so humbly, saying I just feel concerned this is something that shouldn't show up. This was already merged code, but already deployed to staging. So I felt I should be proactive and comment on it.

Then I got my comment closed a few days later, the person made the changes I noted, with no acknowledgement – no reply, nothing.

Now the introvert me is feeling maybe I didn't follow the rules?

I looked at past PR's in the repo. Nearly zero comments. Most of them are self-approved merges.

Did I do something wrong? This is really weird but I don't have a lot of industry experiences.