With the Nasdaq moving to challenge its all time high the question being asked is whether this bull run and move to new highs is a bubble. From my perspective the question is pointless since whether a market could be defined as being in a bubble or not is a function of whatever narrative you apply to it and as I have written before narratives are simply a collection of perceptions and biases. Your narrative reflects both your opinion and your world view and as such they are idiosyncratic to you. You may try and hide your bias within complex analysis and valuation metrics but it is still your bias and it remains a bias because it leads to an opinion of where the market should or should not be.
It is impossible to convince the market of the validity of your narrative (bias) since the market is completely unaware of you or your opinion. it does not matter how tightly you cling to your conviction the market will go in whatever direction it wants to go. And it will go in that direction long after your conviction has crumbled in the face of the reality. Markets will go further, for longer than you could ever imagine.
My view is that there are only two things you can say about the NASDAQ, it has been trending up and it is challenging its old highs. Anything else is guesswork.