It's mostly about what relays each app is using to look for who has you in their follow list.

On Damus, it may try to check as many relays as it knows exist to try and find your follows, or a set list.. Not sure. Would be a question for nostr:nprofile1qyv8wue69uhk6mmwv9jzu6nzx56jucm0d5arsvpcxqqs6amnwvaz7tmwdaejumr0dsqzqvhpsfmr23gwhv795lgjc8uw0v44z3pe4sg2vlh08k0an3wx3cj9zs5e6s or nostr:nprofile1qyxhwumn8ghj7mn0wvhxcmmvqyg8wumn8ghj7mn0wd68ytnhd9hx2qpq3v47pg9dxjq96an8jfev9znhm0k7ntwtlh9y335paj9kyjsjpznq0grx7e .

Primal, on the other hand, just checks its own massive caching relay, which in turn pulls notes in from a large number of other relays.