3.20 Abyss Jewel level requirement changes

I haven't found any information on the level requirement changes to abyss jewels in 3.20. Both of the above jewels had a level requirement of 28 during Kalandra league.

The "avoid being stunned"/Unwavering explicit mod on abyss jewels now apparently only appears on lvl 40 requirement and above.

I play POE to do LLD build theory and also to take my level 28's through act 10 Kitava. Yeah kinda niche. Anyway, these jewels greatly enhanced build variety. However, now LLD builds are again limited to Unwavering Stance, Chayula, and Ezomyte Hold.

What is the reasoning behind the level requirement increase? Why remove consideration for stun immunity during the leveling process? Why buff the values of the unwavering mod greatly a few years ago and then remove it completely for any character under level 40?