Then that’s the problem you should address. Megatopics are not a good idea.
I’d also add if the topic is really that chatty and random, why would you care if you lose your place in reading it? What difference does it make? The idea that your read position needs to be meticulously and accurately tracked becomes nonsensical at that point. If you don’t read some specific part of mega random rambling chat topic, nothing of value has been lost.