Glyphosate itself was discovered back in the 50's; patents around that would have expired ~50 years ago.
The patents around glyphosate resistant soybeans expired five or ten years back; someone immediately produced and released an unencumbered version. (I don't think it's as popular as you'd think; the yields are a bit lower than the state-of-the-art varieties available now, and farmers purchase new seeds every year for a lot of reasons beyond patent encumbrance.)