No it is not and there is actually no significant connection between these two. In fact, miners will be the who gets affected on this as they will get their block reward cut into half again. So, it's gonna be a survival competition for them when this even occur, some might halt and some are upgrading to still maximize their earnings.
One of the main reason why we think bullrun is tied with the bitcoin halving is because of the history we had, that started late in 2017 (post halving) If I'm not mistaken, where bitcoin rose in an unprecedented fashion and everyone was not expecting for that rise, and then followed by the next halving which almost have the same outcome. Now for the 3rd straight halving people are still expecting the same. So, it is the people's perception on Bitcoin halving that could initiate a bullrun.