

Yes.
Ubuntu 24.04 is equivalent to Debian 13, except Ubuntu 24.04 was released last year.
Every Ubuntu version is based on a copy of Debian Sid, which is the unstable branch.
Eventually, they incorporate Debian patches too but keep some packages in different versions (libpng, the kernel, openssl and similar are the most I remember but they change between releases).
No, and also is possible this is due to Debian 13 release plus increment in Lemmy usage in the past years.
I did not notice this before.
I am more around Debian community.