Proposed New OpenPGP Cipher Block Modes Could Cause an Interoperability Disaster

It already is. Gnupg went forward with a good, faster new mode, nobody else can read. As OCB v6. Proton came up with 4 new modes, proton needs. As v5.

They cannot read each other new modes. The best would be to add no new modes at all, but that ship had sailed. (v4) I.e. there are new encrypted files in the wild. Maybe gnupg can add legacy modes to read the new refresh modes v5, and proton an OCB reader for the gnupg OCB mode v6.

https://articles.59.ca/doku.php?id=pgpfan:schism