abrupt speed changes and TCP

So it occurs to me in the rollout of 5G just walking down the street you might shift back and forth between high speed 5G bands and 4G because of uneven deployment and all sorts of other reasons. It sounds like this could vary block by block practically. I assume TCP just views this as congestion? But with all of the congestion avoidance algorithms and the rapidly fluctuating bandwidth, wouldn't that result in the sender essentially adapting to the least common denominator (eg 4G)? The same goes with latency, I suppose for real time apps. Mike