Elasticsearch version:
Version: 7.14.0, Build: default/deb/dd5a0a2acaa2045ff9624f3729fc8a6f40835aa1/2021-07-29T20:49:32.864135063Z, JVM: 16.0.1

JVM version:
openjdk version "11.0.12" 2021-07-20
OpenJDK Runtime Environment (build 11.0.12+7-post-Debian-2deb10u1)
OpenJDK 64-Bit Server VM (build 11.0.12+7-post-Debian-2deb10u1, mixed mode, sharing)

OS version:
4.19.0-14-amd64 #1 SMP Debian 4.19.171-2 (2021-01-30) x86_64 GNU/Linux

Description of the problem including expected versus actual behavior:
We upgraded a cluster from 7.13.4 to 7.14.0. This cluster still uses the deprecated MDP path.data-feature and the old config format using just a comma-separated list as config value for path.data

path.data: /path/to/disk01,/path/to/disk02

Restarting under 7.14.0 yields just one data dir, not both as under 7.13.4.