But you have userChrome.css? You have to update or remove your modifications then.

I tried modifying a bit the userChrome.css file, it seems like the problem is not the tab height itself, the logo in the top right corner got big all of a sudden. Any idea how to remove it?

found in about:config, browser.tabs.firefox-view

Note that you can move the Firefox View button from the Tab bar to the Navigation Toolbar or its overflow area or remove it from the toolbar via the right-click context menu, so no need to disable this feature as it is possible/likely that this pref will be removed once this feature is considered complete.

• https://support.mozilla.org/en-US/kb/how-set-tab-pickup-firefox-view

The Firefox View button has been changed to a folder icon in current releases, controlled by this pref on about:config.

• browser.tabs.firefox-view-newIcon

With this pref set to false you get the 192px about-logo.png icon and not firefox-view.svg. Do you have CSS code in userChrome.css to set this Firefox icon or otherwise have code that sets the height of the tab bar ? We have seen more reports about this icon getting big and it is likely a case of broken CSS that needs an update for 119. Can you post your userChrome.css, so we can inspect it ?

#firefox-view-button {
  list-style-image: url("chrome://browser/skin/firefox-view.svg");
}

• https://searchfox.org/mozilla-release/source/browser/themes/shared/toolbarbutton-icons.css#460
• https://searchfox.org/mozilla-release/source/browser/themes/shared/icons/firefox-view.svg