There are some concerns that adding too much soy protein supplements may increase estrogen and lower testosterone. While there are many rumors circulating, there's a randomized control study that may shed light to this debate. 

Sources: 
 
The effects of soy and whey protein supplementation on acute hormonal reponses to resistance exercise in men

https://pubmed.ncbi.nlm.nih.gov/24015701/

Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men

https://pubmed.ncbi.nlm.nih.gov/15735098/