I use both Threads and Mastodon. However, I realized that sometimes (public) profiles on Threads don’t show up on Mastodon and vice versa. I also realized that most comments made on Threads posts don’t show up on Mastodon – that is, if the posts appear on Mastodon at all. The same is true the other way around. Why does this happen?
This may help explain some of the discrepencies that you’re noticing:
Fedipact - The instances blocking Zuckerberg’s Threads.net
I didn’t know that website, thank you! However, my instance has chosen not to defederate from Threads – according to the source you cited. So, I’m not entirely sure why this is happening.