tomBitonti
Adventurer
There have been some legal threats when some companies went too far.
I know HeroForge had to remove a "squid head" option for their miniature maker because WotC served them with legal notice they felt it infringed on their copyrights for illithid.
Not simply by just being a generic "squid head" option for miniatures, but by showing how their miniature design specifically copied multiple specific design elements of how WotC has consistently depicted illithid since the late 1990's.
I think there have been other cases of companies over-reaching, but they ended with not fighting back, because when it was spelled out to those companies they knew they'd gone beyond acceptable lines and they chose not to fight it.
But, that's a basic copyright case. Illithids are not Open Content. It doesn't seem that the OGL is relevant. Meaning, that case has little or no bearing on the OGL, except to show that the Product Identity of specific depictions of Illithids has a valid copyright. Maybe, if there was a case and a ruling, and not settlement.
TomB