Old (more than 1 year) mails from Inbox suddenly disappeared

Hello,

I'm using yahoo web and suddenly ( find it yesterday) old mails (over 1 year old) were disappeared.

Few years ago, I encountered in the same issue; and what I remember, that I found 

a definition how long to keep the mail in Inbox.

I'm not sure it was in yahoo web, maybe it was on my Iphone device.

( I'm also using outlook app that retrieving Yahoo mails ( pop3)

Is this somehow related the yahoo change of forwarding mails ( Yahoo +) - I'm not forwarding mails.

Thanks in advance

Windows / Edge 107.0.1418.56