FabFilter User Forum
VST3 to VST2
It's not possible to automatically replace VST3 instances with VST2. The other way around should be possible from our next update on though. When a project that uses VST2 is being opened on a machine that only has VST3 installed it will automatically load the VST3 version instead. Unfortunately VST2 does not have the functionality for that.
Ralph (FabFilter) — Feb 11, 2024
how do i switch a plugin from vst3 to vst2