Spouse Visa to GTV

Hi,

I am currently holding UK spouse visa 5-years route which due to renewal on July 2023. I am thinking to switch to GTV as I am currently employed under UKRI grant. I checked on GT Appendix, for ILR under GT route there is a point stated:

GT 10.2. The applicant must have earned money in the UK during their last period of permission in the field in either:
(a) a field related to the subject matter of their prize if they were granted for their initial application using a prize listed in Appendix Global Talent: Prestigious Prizes; or
(b) the field in which they were previously endorsed in the Global Talent route if they were granted their initial application using an endorsement.

Does it mean that I need to be employed within my area of expertise for the 3-years duration of GTV, or can it be anytime during the GTV, and then you work on any type of employment?

I just a bit dilemma whether to switch to GTV or stay on spouse visa, as it is the last year I can apply to GTV through UKVI endorsement.