It should just work. The warning is misleading.
Renoise is a universal binary: It contains an Intel and an Apple ARM version in one bundle. As soon as Rosetta is gone you definitely won’t be able to use the Intel version of Renoise via Open with Rosetta, but the ARM version should work just fine.
Not sure why Apple now is flagging app bundles that also contain intel slices. I think it’s unlikely that universal binaries fail to load in future, but Apple is known for surprises in this area 