Responses
I dont think thats the case, Saitama is 25 years old and in this chapter we see blast with a young tatsumaki, She is older than Saitama so this would mean that around that time Saitama would also be around that age, way before he gained his strength.
What if blast just got amnesia and became saitama? I mean there's a huge gap from when we saw him training to him now and saitama only recently gained popularity despite having been strong for so long, like u would expect that he would have been exposed already before he even met genos (also blast has the same hairstyle as saitama before)