Hard to say from the outside. Most founding teams end up with around 20% of a company at IPO so you could use that as a reference point.

However, this company was a few stages before IPO so there could have been less dilution from investors - allowing the founders to get a bigger cut.

On the other hand, some investors have really aggressive terms that can screw founders in situations like this. For example, their contracts could stipulate that an investor gets the first $45m of any exit even if that investor only put $15m into the company.