I know some vegans who would disagree with that
I definitely would!
Usually, the reason people go vegan is to try to reduce (hopefully eliminate) animal suffering, and/or to reduce green house gas emissions from animal farming.
Cultivated meat deals with the first, and, depending on how it's produced, can probably entirely avoid the second as well.
I don't know the process in detail, but I would also imagine that cultivated meat is no more sourced from animals than a plant that was fertilized with animal dung, and that would still be considered vegan.