An old answer of mine just got an upvote, which caused me to look at it again, and I was surprised to discover that my HTML tags for italics (that is the letter $i$ between two pointy brackets) were not rendering. This made the answer almost impossible to read, because I had used italics instead of blockquotes to set off quotes from the original question, but the italics weren't rendering, so those quotes and my responses were all run together.
Aside from the fact that this makes the upvote a little mysterious, this makes me wonder whether something has changed and HTML tags that used to render properly no longer do so. If that's the case, then a lot of old posts (not just mine) probably need to be edited accordingly.
This is made more mysterious by the fact that when I attempted to type italic tags in this post, wanting them not to render, they did render, forcing me to go back and write the phrase "the letter $i$ between two pointy brackets". So is there a difference between the main site and meta? Or between questions and answers? Or something more obscure?
I'm using the "bug" tag for this, though of course part of my question is whether this is a bug.
Edited to add: The original version of the post that triggered this is here: https://physics.stackexchange.com/revisions/350351/1. I see now that this actually renders properly on my laptop, though not on my phone. In the two revisions that follow, I replaced the italic tags with blockquotes.