Watching episodes of a Series prior to the current.

I have both Netflix and Apple TV and I find it easer to go to previous episodes on Apple TV because all you need to do is scroll down on the screen after choosing the show and on Netflix it requires you to choose the Episodes & More option. The same is true for Pluribus.

If you are in the Continue Watching section of Apple TV, then it will take you to the next episode as that is the purpose of continuing to watch a series, so in that case you can choose the button with 3 dots and then "Go to Show" where you will see all the episodes by scrolling down on the screen.

Depending on the device, you may have a different action to access the additional information in the Continue Watching section. For example when watching on a TV, then a long press on the show will bring up the additional options and you won't have the button with 3 dots to press.

As for Netflix, I don't like the fact that there is no way to continue watching a series you started unless you add it to your List first. Otherwise you have to try and find the show you were watching previously. With Apple TV, that is all done automatically once you start watching an episode and will show in the Continue Watching section.

Where or on what device are you having this issue exactly?

I can see all the episodes just fine. Apple does not hide anything.