Explaining auto cache behavior

I feel like something changed here, and just asking to be sure this is supposed to work this way…

Have an older ATV4k 32gb running 16.3. Latest versions of Infuse. I exclusively stream from my Plex server. When I start a video, I see a lot of traffic from the Plex server and NAS, aggressively caching (fine so far). At some point I can see the progress bar seems to show a “decent” amount of cached content. The traffic pretty much stops there. But, the cache isn’t seeming to pull more to stay kinda full, it seems to not fetch more until exhausted - then I see a constant (much slower) traffic from the Plex server.

I seem to remember this used to be different, where it would try to periodically pull a burst at faster transfer rate. It’s not that the current situation is pausing or stuttering, just seems like skipping forward might be a bit slower (since there’s not a big buffer).

Am I wrong with this recollection? Or has this changed?

This will depend on your cache setting. The differences are discussed here.

I understand that, and I’ve read that. I use the auto mode, and have always used the auto mode. But it appears that that behavior is different now, and wondering why.