Apologies if this particular issue with macOS running Big Sur has already been covered. I decided yesterday to cancel my Adobe yearly subscription which renews next April. I now use Dx03 almost exclusively. I have already installed a purchased copy of Lightroom 6 so I thought I'd fire it up to check it's usability. I discover that I can't even load it, turns out that it's a 32 bit application and Big Sur won't recognise it!
Fortunately I have Win10 machine which I have primarily used for my 32bit games and other stuff that macOs handles badly such as some firmware updates. After much faffing about I've cleared this pc of all Adobe applications and successfully re-installed Lightroom 6. I've also been able to install my version of DxO 3 on that machine so I can try to integrate the two applications.
I sometimes feel that I'm being boxed into a corner by companies like Apple and Adobe with their sunscription policies and also reduction of usability following OS "upgrades".
I'd love to be able to use my iMac for everything but I can't, I have three keyboards on my desk!