So can you say vaccines are the reason? No, you can't.
Sure I can and with a decent amount of evidence to that effect. Israel reported 64% for a short period and not a huge sample size, other jurisdictions said 88% vs. delta and delta+. Even Israel stated 93% prevention of hospitalisation and serious illness with their current run of variants. The evidence is overwhelmingly in favour of vaccination.
So in short, no. What would the current situation be without vaccines? How about the Spanish flu? That seemed to peter out in about the same time frame, no vaccine.
Again, no surprise when something burns through and peters out. Same as it's ever been. Besides, it's difficult to talk anyone serious that uses a U in favor.
