Resignation while UK ICT Visa Extension is in process

[gopicharan]

My ICT Visa is valid until 17th August 2022. My employer has initiated extension of my ICT visa and my visa interview is on 4th July 2022 (Normal processing - 8 weeks for results).
Now, I am planning to resign and move to the US.
My question is, if I give my last working day as 31st August 2022, will it cause any trouble to maintaining my ICT visa status as my current visa ends on 17th August 2022 and the extension under normal processing timelines may or may not be on time. And, there is a risk of employer cancelling my extension and I may go out of status.
What is advisable? Is giving my last date before 17th August 2022 the safest route as abandoning my extension will not cause any issue with respect to maintaining my status until last working day?
Please help.