RSS feed not updating properly

Hello, today my Mint Update Manager offered me an update to version 115.16.2. I was still waiting for a version 115.16.1 update to my installed version 115.16.0 (RSS feed had 115.16.1 on the 14th day). So the PPA Mozillateam skipped the 115.16.1 version completely for some reason (and ubuntu repo is still at version 115.16.0).

But the problem is that the RSS feed still doesn't have the version 115.16.2 in it. It was released on the 17th day, so I guess the RSS feed generation is faulty somehow?

Additionally, the RSS feed shows updates to version 131, although the actual releases page does not show that "branch" at all.

Also a side question, if I may, is there a date set when linux users are automatically updated to version 128 branch? I'm seeing this:

$ apt policy thunderbird

thunderbird:
  Installed: 1:115.16.0+build2-0ubuntu0.20.04.1~mt1
  Candidate: 1:115.16.2+build1-0ubuntu0.20.04.1~mt1
  Version table:
     1:115.16.2+build1-0ubuntu0.20.04.1~mt1 501
        500 http://ppa.launchpad.net/mozillateam/ppa/ubuntu focal/main amd64 Packages
     1:115.16.0+build2-0ubuntu0.20.04.1 500
        500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
 *** 1:115.16.0+build2-0ubuntu0.20.04.1~mt1 100
        100 /var/lib/dpkg/status
     1:68.7.0+build1-0ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages

From the release notes I can see that the version 128.2.0 was the first version that did NOT say the following anymore:

Thunderbird version 128.0 is only offered as direct download from thunderbird.net and not as an upgrade from Thunderbird version 115 or earlier. A future release will provide updates from earlier versions.

Version 128.2.0 was released on September 4th, over 6 weeks ago.

I do have to admit that I find the versions, release channels, "esr" branding and updating stuff a bit confusing.

Start by comparing the RSS feed at thunderbird.net/en-US/thunderbird/releases/atom.xml with the releases page linked in the report, checking the missing 115.16.2 entry and the unexpected 131 entries. Done means the feed matches the published releases and the separate Linux update question has a documented answer or clear scope.