Losing Minimised Windows

I have recently transferred to Windows 11, and use Firefox/Google to access websites. But now if I minimise a window into the taskbar and open another website this replaces the first one, which is then lost. I used to be able to have several active sites minimised together in the taskbar, any of which could be brought up as required. I'm sure this can be easily fixed, but how? I have followed earlier advice to tick the Never combine icons button but this has not solved the problem.