basically 7nm+ means tweaks to the process with improved speed and power consumption, stays 7nm from [0]

""" TSMC plans to introduce a second improved process called 7nm+ a year later, which will introduce some layers processed with EUVL. This will improve yields and reduce fab cycle times. The 7nm+ process will deliver improved power consumption and between 15-20% area scaling over their first generation 7nm process. """

[0] https://en.wikichip.org/wiki/7_nm_lithography_process

update: link