Sadly Plex seems not to have any level of focus on usability or stability for Plex on iOS / iPadOS (or MacOS).
I’ve escalated to the CEO, CPO (and founder) and other executive level folks, that got at least one reply from a senior leader, that didn’t yield any steps forward. I’ve provided countless rounds of detailed logs and documented everything I possibly can. I’ve even tried totally erasing my iPad and installing only Plex, not doing any downloads, and absolutely nothing,
https://forums.plex.tv/t/plex-client-on-ipados-crashing-at-least-5-7-times-a-week
I hope your experience is different, however the sad truth is that Plex on iOS, iPadOS & MacOS is abandonware at this point. On iOS/iPadOS Plex isn’t stable, downloads don’t work reliably (and during the limited times they do they are ridiculously slow), no support for Airplay, no support for stage manager when an external monitor is connected…and more.
I’ve moved to paying for and using Infuse, just to get a stable video playback experience with my Plex Server. The most annoying thing is, the only reason I got a Plex lifetime pass was for downloads and iPad player, neither of these features work…so a total waste of money IMHO.