Build failure: USE Flag 'pgo' not in IUSE for www-client/torbrowser-68.8.0_p9010

[papjul]

As the title says.
I also notice what seems to be a warning "Please call python_get*() instead." maybe due to a recent move from Python 3.6 to Python 3.7.

 * Package:    www-client/torbrowser-68.8.0_p9010
 * Repository: torbrowser
 * Maintainer: [...]
 * USE:        abi_x86_64 amd64 clang cpu_flags_x86_avx2 dbus elibc_glibc kernel_linux startup-notification system-av1 system-harfbuzz system-icu system-jpeg system-libevent system-sqlite system-webp userland_GNU
 * FEATURES:   ccache network-sandbox preserve-libs sandbox userpriv usersandbox
 * Using python3.7 to build
 * python_export() is part of private eclass API.
 * Please call python_get*() instead.
 * Will use LLVM slot 10!
 * ERROR: www-client/torbrowser-68.8.0_p9010::torbrowser failed (setup phase):
 *   USE Flag 'pgo' not in IUSE for www-client/torbrowser-68.8.0_p9010
 * 
 * Call stack:
 *                        ebuild.sh, line 125:  Called pkg_setup
 *   torbrowser-68.8.0_p9010.ebuild, line 206:  Called use 'pgo'
 *                 phase-helpers.sh, line 247:  Called die
 * The specific snippet of code:
 *                              die "USE Flag '${u}' not in IUSE for ${CATEGORY}/${PF}"

Thank you!

[MeisterP]

"Please call python_get*() instead."

This comes from an eclass and should be fixed there.