Sorry for the delay Tony!
I discovered the problem because I'm helping in the development of https://github.com/fiatjaf/njump, that now also support long form content:
Now you don't see any problem, but is merely a "regex coincidence" that I causally hit and decided to keep because should not give problems :)
I never heard about the < ... > syntax, I would suggest to use the standard one or the "url only" simplified version that every client already use for short notes, so presumably it is supported also in the long format.
PS: I encourage you to use https://nostr.com/
Bonus point: it is search engine friendly, so the article is proper indexed and we can attract more people on nostr!