These waves do not exist.
this is just lazy MSM wanting to just make generalisation.
The 2nd Wave as it was called by the media was different in that it had the concept of a Women's Liberation Movement.
Since then the media and academics have waffled on about this or that wave, or equally lazy promoted individual women who happened to have decided they have enough insight to write a book. None of which actually reflects what was going on.
If you are really interested you would be setting up oral history projects in different areas and find out what if any women actually did.
Writing stuff, and commentating isn't about anything other than an individuals personal opinion.
eg look at this description of waves. https://www.feministsinthecity.com/blog/a-brief-history-of-feminist-waves
Feminism or women's activism is not to be found in in essay's that wouldn't get the writer any marks in a secondary school.
If interested why not asking women on FWR what is the centre of their feminist practice. ie what do they actively do, as opposed to having an opinion.
If anything if there ever were waves they have all been submerged by virtual media chit chat.
(And of course hopelessly euro and us centric!)