Previous versions are available on apkpure. I rolled back to 5.7.19 on Sunday. Be sure to untick automatic updates in the app setting in google play or it will download v6 automatically again.
As much as i like lingq and i bought the lifetime of the language im learning i need a system on mobile that functions. V6 does not at all. It looks nice but the core functionality is useless to me until its fixed.