ERROR: tox config file (either pyproject.toml, tox.ini, setup.cfg) not found

The following error occurs in versions 6.1 and 6.2. Version 6.0b15 works fine

ERROR: tox config file (either pyproject.toml, tox.ini, setup.cfg) not found
Error on isort-apply: 
ERROR: tox config file (either pyproject.toml, tox.ini, setup.cfg) not found
Error on black-enforce:

To reproduce it:

PLONE_VERSION=6.0.0b3
PLONE_HOME=/home/Plone-${PLONE_VERSION}

mkdir -p ${PLONE_HOME}/src
rm -rf ${PLONE_HOME}/src/myaddon.name
cd ${PLONE_HOME}/src

cat <<EOF > ${PLONE_HOME}/src/myvariables.ini
[variables]
author.name = theAuthor
author.email = mail@domain.com
author.github.user = GitHubUsername
package.description = An add-on for Plone
package.git.init = True
package.git.autocommit: True
plone.version = 6
python.version = python3.9
vscode_support = False
EOF

${PLONE_HOME}/bin/mrbob --config ${PLONE_HOME}/src/myvariables.ini -O ${PLONE_HOME}/src/myaddon.name bobtemplates.plone:addon

plone / bobtemplates.plone

ERROR: tox config file (either pyproject.toml, tox.ini, setup.cfg) not found #528