Remove AEAD flag

Unfortunately, this is not working for me.

I modified my public key as @markdascher suggested.

% gpg --edit-key B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B
[... do the thing ...]
% gpg --edit-key B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B
[...]
gpg> showpref
[ultimate] (1). Philip Paeps <philip@trouble.is>
     Cipher: AES256, AES192, AES, 3DES
     AEAD:
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, Keyserver no-modify
[ultimate] (2)  Philip Paeps <philip@freebsd.org>
     Cipher: AES256, AES192, AES, 3DES
     AEAD:
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, Keyserver no-modify

I verified that the AEAD prefs were actually gone by comparing the output of gpg --list-packets before and after:

% diff -u pubkey.asc.txt pubkey-no-aead.asc.txt
--- pubkey.asc.txt	2021-06-23 13:02:50.000000000 +0800
+++ pubkey-no-aead.asc.txt	2021-06-23 13:18:58.000000000 +0800
@@ -5,39 +5,37 @@
 	keyid: BB6D8A14AFE7D96B
 :user ID packet: "Philip Paeps <philip@trouble.is>"
 :signature packet: algo 22, keyid BB6D8A14AFE7D96B
-	version 4, created 1621924124, md5len 0, sigclass 0x13
-	digest algo 10, begin of digest 91 fe
+	version 4, created 1624424244, md5len 0, sigclass 0x13
+	digest algo 10, begin of digest 13 22
 	hashed subpkt 27 len 1 (key flags: 03)
 	hashed subpkt 9 len 4 (key expires after 2y37d5h32m)
+	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 25 len 1 (primary user ID)
+	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
+	hashed subpkt 2 len 4 (sig created 2021-06-23)
 	hashed subpkt 11 len 4 (pref-sym-algos: 9 8 7 2)
-	hashed subpkt 34 len 2 (pref-aead-algos: 2 1)
 	hashed subpkt 21 len 5 (pref-hash-algos: 10 9 8 11 2)
 	hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
-	hashed subpkt 30 len 1 (features: 07)
-	hashed subpkt 23 len 1 (keyserver preferences: 80)
-	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
-	hashed subpkt 2 len 4 (sig created 2021-05-25)
-	hashed subpkt 25 len 1 (primary user ID)
+	hashed subpkt 30 len 1 (features: 05)
 	subpkt 16 len 8 (issuer key ID BB6D8A14AFE7D96B)
 	data: [256 bits]
-	data: [256 bits]
+	data: [255 bits]
 :user ID packet: "Philip Paeps <philip@freebsd.org>"
 :signature packet: algo 22, keyid BB6D8A14AFE7D96B
-	version 4, created 1621924146, md5len 0, sigclass 0x13
-	digest algo 10, begin of digest c7 b2
-	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
-	hashed subpkt 2 len 4 (sig created 2021-05-25)
+	version 4, created 1624424254, md5len 0, sigclass 0x13
+	digest algo 10, begin of digest 8f e8
 	hashed subpkt 27 len 1 (key flags: 03)
 	hashed subpkt 9 len 4 (key expires after 2y37d5h32m)
+	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
+	hashed subpkt 2 len 4 (sig created 2021-06-23)
 	hashed subpkt 11 len 4 (pref-sym-algos: 9 8 7 2)
-	hashed subpkt 34 len 2 (pref-aead-algos: 2 1)
 	hashed subpkt 21 len 5 (pref-hash-algos: 10 9 8 11 2)
 	hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
-	hashed subpkt 30 len 1 (features: 07)
-	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 30 len 1 (features: 05)
 	subpkt 16 len 8 (issuer key ID BB6D8A14AFE7D96B)
-	data: [253 bits]
-	data: [255 bits]
+	data: [256 bits]
+	data: [256 bits]
 :public sub key packet:
 	version 4, algo 22, created 1621924204, expires 0
 	pkey[0]: [80 bits] ed25519 (1.3.6.1.4.1.11591.15.1)

Selecting that key from keybase select pgp --multi still returns the same error:

▶ ERROR key generation error: Unknown signature subpacket: 34 (error 905)

Originally posted by @ppaeps in #4025

Start by reproducing the failure with keybase select pgp --multi and the reported gpg --list-packets output, focusing on the unknown signature subpacket 34 error. Trace the key-selection and PGP parsing entry points in the Keybase client, then verify that a key without the AEAD preference no longer produces error 905.