Uninstall/reinstall is only a temporary workaround, as @SikSikWolf said. When the app tries renewing auth (I assume--I'm not testing it fully for free), then the white overlay obliterates all content again.
That is, I had most of yesterday with a functional app after reinstalling, and this morning I have the blocking overlay again.
Paying won't help; I've been a paying customer for years.
Reinstalling daily for a recently introduced bug seems to me to be really poor UX. I guess disabling the passcode would be the real workaround, but I have solid reasons for keeping a passcode in place. @agsteele