OK, I can see this error, too:
Error: Error pulling from repo: While pulling app/org.mozilla.Firefox/x86_64/eos3 from remote eos-apps: Writing content object: Corrupted file object; checksum expected='858198e119764658a555fc4d12fdef6bd76f4a9a682f708743339c9e1587b7bc' actual='03c37bd0b94aad3efb503afaca7ec820d95290ec4237c32623e8821db079b59a'
error: Failed to install org.mozilla.Firefox: Error pulling from repo: While pulling app/org.mozilla.Firefox/x86_64/eos3 from remote eos-apps: Writing content object: Corrupted file object; checksum expected='858198e119764658a555fc4d12fdef6bd76f4a9a682f708743339c9e1587b7bc' actual='03c37bd0b94aad3efb503afaca7ec820d95290ec4237c32623e8821db079b59a'
A workaround for this issue is to install Firefox with the following command:
pkexec flatpak install eos-apps org.mozilla.Firefox
We’re working on putting a newer version of Firefox into the app center anyway – and it would resolve this issue. I don’t have a timeline for this yet.