Character / User Chip in Markdown breaks HTML

Via this profile: https://refsheet.net/Kaemone/rosa

Character / user chips (the @ tag thing) is generating broken HTML that ends up looking like:

```
<p<a href="#">Chip and Whatever else followed...</p<a>
```

It looks like the Markdown parser is, for whatever reason, reading the inserted tag as a `p<a` thus <`p<a`>...</`p<a`>.

Fascinating.