On Win11 I run Mullvad browser in Sandboxie Plus, for any sites I'm unsure about, with uBlock Origin.
My otherwise main working browser is Librewolf, unsandboxed, also with uBO. I use Simple Tab Groups to separate my working spheres, which I find excellent. I tried Firefox profiles, but it's rather, urgh, primitive (unfortunately!).
Use Firefox sync with LW to sync between laptops (Win11 Pro and Fedora/Gnome).
Forgot the 'Why?'
I've always stuck with Firefox, locked down or hardened. But as has been written extensively elsewhere, the process of 'hardening' can be hit and miss. When these two LibreWolf and Mullvad browsers came along, I find they suits my needs perfectly, together. Mullvad browser always starts afresh, so it gets used for my surfing 'in unchatered waters' (sandboxed), and any sites I want to keep hold of, in whatever respect, I copy over to Librewolf.
I guess it's a cautious way of surfing. I use uBO in Advanced mode but I certainly don't know enough about staying safe, so this is my attempt at keeping things undeer control as much as my knowledge/ability lets me.
Edit: I also use Firefox with Containers in an attempt to keep online banking and shopping 'separated'.