Compost differences

There's a Youtuber I watch who planted in to raised beds filled with 60% green waste compost, and nothing grew well. He had the soil analysed and it was really, really high in nutrients. Bearing in mind 30% of the mix was peat, which is very low in nutrients, the levels of some nutrients like potassium and phosphorous were up to 10x higher than is considered healthy. So I guess if this Supagrow stuff is 100% green waste, it's just too strong for young plants.