Probably your follow list doesn’t fit in most nostr relays. We have categorized people sets so using that you can “follow” as many people as a normal human would want.
It’s interesting and another way nostr has changed my social network usage. On Twitter and other networks it’s not out of the ordinary to follow thousands of accounts. Before even hearing about issues with relays and follow lists being too large, I noticed on nostr that once I got above 900 follows my feed got too noisy. I’ve tried to keep mine around 500-600-ish and that has worked out well. Good amount of my content in my feed, not too noisy.
its not the list itself, its clients struggling to batch their reqs.