New 2015 15" MacBook Air occasionally pauses for 30 seconds?

I have a new 15" MacBook Air (M4, 24gb 2tb). I installed data from a Time Machine backup on Wednesday on top of its macOS Tahoe and it has been working ok.

However, I've noticed that every so often it freezes for 30 seconds - if I have a video playing it keeps working, but neither the keyboard nor touchpad are responsive. It has happened five or six times in the past two days. I can't find any obvious trigger for it, but it's annoying.

FWIW when the device was installed first it had Tahoe 26.0 and I updated it to 26.1 this morning - the problem continued after the OS update.

I had a 2019 MBPro that never had this problem, so it's frustrating to now have to deal with it on my new 'Air.