We pre-configure the flathub remote for flatpak when building images, however this seems to be broken at least on the systemd branch (but likely affects edge too).
On a fresh install, running flatpak remotes shows flathub as expected, however flatpak remote-ls yields
error: Unable to load summary from remote flathub: Signature made Sat Nov 16 19:28:38 2024 using RSA key ID 562702E9E3ED7EE8Can't check signature: public key not found
I took the .flatpakrepo file from flathub.org and packaged it in pmaports here, and that file is installed in the rootfs at a location that flatpak autoloads remote config from. As of the posting of this comment, those files are identical, so I don't think keys changed, maybe they expired and no one has noticed on flathub.org?
I've seen vague 'key not found' errors in the past elsewhere when the system clock was wrong. The next time this is reproduced, can you immediately check that the system time is correct?
qcom-msm8953:~$ date && flatpak remote-lsFri Nov 22 21:33:16 +04 2024error: Unable to load summary from remote flathub: Signature made Fri Nov 22 21:23:56 2024 using RSA key ID 562702E9E3ED7EE8Can't check signature: public key not foundqcom-msm8953:~$
qcom-msm8953:~$ flatpak remote-add --verbose --user --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepoF: Opening user flatpak installation at path /home/vipaol/.local/share/flatpakF: Loading https://flathub.org/repo/flathub.flatpakrepo using curlF: Received 4040 bytesF: Imported 1 GPG key to remote "flathub"F: Clearing cached summaries for remote flathubF: Fetching summary index file for remote ‘flathub’F: Loading https://dl.flathub.org/repo/summary.idx using curlF: Received 10001 bytesF: Loading https://dl.flathub.org/repo/summaries/8d5ae9378ebd01f83517c7c5e08f484a037be8b60746276b11c962515753a082.idx.sig using curlF: Received 592 bytesF: Fetching indexed summary file e8df6546c1f060ea240d0db0c1e98cbe5aef8900021274ab2e18f60a55d792c9.gz for remote ‘flathub’F: Loading https://dl.flathub.org/repo/summaries/e8df6546c1f060ea240d0db0c1e98cbe5aef8900021274ab2e18f60a55d792c9.gz using curlF: Received 776005 bytesqcom-msm8953:~$ flatpak remote-lserror: Unable to load summary from remote flathub: Signature made Fri Nov 22 21:38:40 2024 using RSA key ID 562702E9E3ED7EE8Can't check signature: public key not found