Mac OS Ventura 13.3 minimize FF window with red bulb and reopen, starts as clean start

[LePaul]

After updating my Mac I have a weird problem with Firefox 111.0.1 as follows:

• Open FF
• Startpage (for me: Facebook) opens
• Add a few tabs with different sites
• Minimie FF with the red button (FF stays active)
• Reopen FF by clicking the icon in the dock
• FF re-opens but with start page only