What is this plastic strip inside my laminate flooring?
The 5G locking system uses a set of plastic clips on the inside of the
groove to hold the attached plank in place. You will hear a slight
audible click when you’ve installed the planks correctly. See the
installation video demo below for a visualization of how to install a
5G locking system flooring.
https://www.bestlaminate.com/blog/the-difference-between-5g-and-megaloc-locking-systems/


The panels use a tongue-and-groove “Clic” system that lets you simply
snap panels together...
https://m.kronotex.com/Laminate-Flooring-Guide/Installing-snap-together-laminate-flooring-1419384348.html