Currious IMAP server response for Yahoo! account. Uncleaned buffer?

Mac OS 26.7.1. There are 2 responses to IMAP command 103. IMAP command '104 IDLE' between the 2 responses. The first one is correct. The second one!!! is identical to the first one except it is prepended with the letter 'p'!!!. Always the letter 'p'. It looks like a programming error. Note that the entry in prefs.js for this main account is broken since migration for Thunderbird 155.0.1 to 156. Every time I change some settings in the Identity section, 2 prefs.js entries are removed: mail.identity.id1.fullName and mail.identity.id1.useremail. This prevents me from sending emails from this account until I enter the proper values from the Prefs editor. I realize this is 2 problems but I think one may cause the other. Note that I have a second Yahoo! account that works perfectly well. Thanks for any advice. 330626000.txt: 2026-10-24 16:23:22.455152 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:A:SendData: 93 ID ("name" "Thunderbird" "version" "158.0.1") 2026-10-24 16:23:22.946354 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:A:CreateNewLineFromSocket: * ID ("version" "1.1.26730" "host" "localyahoo.serving-api.mail-serving-jimap-prd.gcp.yahoo.cloud" "name" "Y!IMAP" "vendor" "Yahoo! Inc." "support-url" "http://help.yahoo.com/" "remote-host" "67.195.177.120" "via" "jimap400041.imap.mail.yahoo. yahoo.cloud|localyahoo.serving-api.mail-serving-jimap-prd.gcp.yahoo.cloud") ... 2026-10-24 16:25:51.321640 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:ProcessCurrentURL: entering 2026-10-24 16:25:51.321712 UTC - [Parent 23990: Main Thread]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:SetupSinkProxy: got m_imapMailFolderSink 2026-10-24 16:25:51.321793 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:ProcessCurrentURL:imap://XXXXXXXX.XXXXXX%40ymail.com@imap.mail.yahoo.com:993/select%3E/INBOX: = currentUrl 2026-10-24 16:25:51.323962 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:SendData: 102 noop 2026-10-24 16:25:51.866542 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:CreateNewLineFromSocket: 102 OK NOOP completed 2026-10-24 16:25:51.866628 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:SendData: 103 UID fetch 388684:* (FLAGS) 2026-10-24 16:25:52.088074 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:CreateNewLineFromSocket: * 9700 FETCH (FLAGS (\Seen $NotJunk) UID 388683) 2026-10-24 16:25:52.392757 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:CreateNewLineFromSocket: 103 OK UID FETCH completed <<<<============ 2026-10-24 16:25:52.426006 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:ImapThreadMainLoop: idlePending set 2026-10-24 16:25:54.431078 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:SendData: 104 IDLE 2026-10-24 16:25:54.544903 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:CreateNewLineFromSocket: + idling 2026-10-24 16:25:54.545022 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:HandleIdleResponses: idle mode async waiting 2026-10-24 16:28:20.264066 UTC - [Parent 23990: IMAP]: I/IMAP 330626000:imap.mail.yahoo.com:S-INBOX:CreateNewLineFromSocket: p103 OK UID FETCH completed <<<<============ p103 OK UID FETCH completed !!! (Server error or client error?)