There is something wrong in Cubase when changing project’s samle rate. When offline edits are present in project (variaudio etc.), cubase produces strange audio effects (extremely weird and unusable on vocals). AFAIK Cubase samplerate converter in Cubase 12 is pretty great, industry top quality, but it’s pre-function, boucing offline edits, creates garbage sound.
Workaround is to rebounce all tracks manually (i.e. no offline edits) and then resample project to a new sample rate…