Zen browser: Tabs are all over the place and get messed up frequently

[freijon]

Steps to reproduce

• Open Zen browser in a new profile
• Install Sidebery
• Open a LOT of tabs with sub-tabs and groups in different panels
• After some time, the issue occurs, but I can't provide a 100% step-by-step guide how to reproduce

Actual behavior

• When I click a link with (open new tab), the tab doesn't show up at all in Sidebery. Only after a reload of the add-on do I see the new tab
• Sometimes entire tab structures get moved unintentionally from one panel to another panel
• Sometimes all my tabs disappear. After a reload, they are back, but mixed with some tabs from other panels
• When the mixup happens, the tabs also lose their structure and are often no longer below their previous parent tab

This happens on Zen on my work machine (Windows) and also on my personal Linux machine It was also not like this from the beginning, I feel this is some kind of regression. I'm testing native Firefox now to find out if the issue is caused by Zen or not. I still want to use the addon, but it's barely usable like this.

Expected behavior

Don't mess up my tabs

System

Windows 11 & Gentoo Linux

Firefox version

Zen 1.14.11b (Firefox 141.0.3)

Sidebery version

5.2.0

Logs