I guess SaaS license is where the gap is. I will try an example...

I guess SaaS license is where the gap is. I will try an example here from what I understand, correct me if wrong.

Old licensing model:
Company A signs 3 year contract (unbreakable) with Nuix worth 3M in FY21 Nuix books revenue 3M in FY21, easy to understand

SaaS model:
If company decides to switch to SaaS contract.
Depends what the pricing and usage is, Nuix books the minimum volume eg, 0.1M in the 1st month. Since they only mentioned SaaS migration early this year, assuming only used less than 6months worth of SaaS in FY21 results in maybe 0.5M, so Nuix book 0.5M

this is potentially a -2.5M difference in accounting, however with more data/cases processed, it will continue generating revenue in FY22, FY23 all depends on how much is used. But according to many cases from other company's journey to SaaS, it will eventually surpass perpetual licensing.
The key is pricing and increasing data usage over years.