Old new mail detect still fails in some circumstances

[Ximi1970]

Describe the bug API count method disabled. New mail shading still active when there are no new mails.

To Reproduce API count method disabled. Receive new mails, goto the mails and delete them quickly. or select more then one and select delete.

Expected behavior New mail shading should disappear.

Desktop (please complete the following information):

• OS / distribution: Leap 15.6
• Architecture 64bit
• Desktop type / Window Manager KDE
• Thunderbird version and arch: Tb115 / Tb128 64bit
• Thunderbird package type: mozilla binary, repo
• Run echo $XDG_SESSION_TYPE : x11
• Add-on version: git
• App version: git
• Install type: github repository build.
• Used Qt library: default system repository