Yeah - this is a big factor.

My home internet gets ~7ms to London (I'm in the UK, London is the important IXP. My test is to one of my ISP's routers at LINX). 5G is about 40ms.

When you add load, my home internet stays at about 7/8ms (CAKE is wonderful!), but my 5G goes to 200-600ms.

No doubt about that. Also my fiber optic connection latency increases a bit under load.

latency under load is next up for public awareness, hold on tight