10K limit on joins
There are two kinds of songs that add up to the total count of songs that you in your Smule profile. The songs that you posted yourself (joins with others, solos, group songs) and the songs that others posted by joining your invites.
When you install Duets.fm, you would see at most 10,000 songs that you posted. For each invite within those 10,000 songs, you would see up to 10,000 joins from others. This 10,000 restriction is imposed by Smule.
This does not restrict the total songs in the app. Including others' joins to one's invites, there is no realistic limit on the total songs in this app.
This also does not restrict new songs that you post moving forward. The app will continue downloading them, even if you cross the 10,000 limit on the number of songs you post.
Here is a hypothetical scenario:
Say, a singer joined Smule on 1/1/2013.
She posted 2,000 songs from 1/1/2013 to 1/1/2017. These
posts include both her joins with others’ and her invites. There were 6,000
joins from others on her invites during this time. So, on 1/1/2017, her Smule
profile would have shown 2,000 + 6,000 = 8,000 songs.
On 11/11//2023, she installed Duets.fm. Between 1/1/2017 and
11/11/2023, she had posted 10,000 songs. There were 50,000 joins from others on
her invites during this time. On 11//11/2023, her Smule profile would have shown
8,000 + 10,000 + 50,000 = 68,000 songs.
After installing Duets.fm, she posted 100 more songs. There
were 900 more joins from others on her invites during this time. Now, her Smule
profile would show 68,000 + 100 + 900 = 69,000 songs.
In Duets.fm, she would see 61,000 songs. She will not see the 8,000 songs from 1/1/2013 to 1/1/2017. She will see all the other songs.