These products work with Big Sur:
Icarus2
Electra2
Nemesis
Warlock
Saurus2
Gladiator3
UltraSpace
Akustix
These products are not compatible with Big Sur:
FilterBank
BiFilter
Warmverb Multi-FX
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Sadly Apple does not care much about the downward compatibility and quickly deprecates technologies.
If you are working in a professional environment and want to be sure that your plugins, song-projects, software, dongles, drivers and hardware will work also several years later you should consider to migrate to Windows. Windows has drastically improved since the last years. Today it is a very stable and reliable operating system. Microsoft does make big efforts to keep things compatible with updates. Nearly all hosts are also available on Windows.