Nodes will rate limit them, nodes that don't have rate limits will keep dropping older data.

It is a sloppy network, you should never expect the DHT to give you perfect reliability. 

But just like you don't query the DNS root servers directly, you don't need to query the DHT directly, you can use relays with bigger cashes and more robust rate limiting and only rely on the DHT for things you haven't seen before.

obviously that also means that you shouldn't update your Pkarr too often, because long TTL is a big part of the reliability and scalability