What's with

It's hard to expect a movie like this not to borrow certain elements from time loop movies or books that were done before. Unfortunately, I don't remember the title of the movie but the main protagonist was repeating some period in his life over and over again losing certain parts of his health. Similar things happen in "The Men Who Murdered Mohammed" by Alfred Bester or "UBIK" by Philip Dick.

I believe the movie was a metaphor for Nadia and Alan being stuck in their own lives, unable to change or move forward. The fruit rotting shows time keeps going even when it seems everything stays the same. The fish, I can't even guess.

So, okay, I'll try to explain, but I'm not sure I get it myself...here goes...

Fruit, flowers, and fish have to do with the messed up timelines. Nadia talks about it a bit. Everything resets, but somewhere time is moving foreward without them, so the world is decaying. Entropy is still happening. This is probably why people start disappearing, too: the fabric of reality is ripping apart as they circle the drain.

So, you're right with the time stop thing, I think. Nobody notices because these parallel worlds aren't "right", so the people in them aren't behaving normally. Maxine spinning around by herself, for instance. They mostly seem "normal", but as the worlds collapse, they behave slightly more erratic.

Mirrors are connected with the mom. The mom smashes all the mirrors. Remember Ruth talks about the mirrors reminding people of existence and never being alone. So as the world falls apart, they're more "alone" and existence is more tenuous.

Who's eating cake?

I don't know why the necklace stayed. I think the ring disappeared because they were changing things in a BIG way. As they made progress, they got closer to the alternate-world event horizon or something like that, so that caused permutations in the realities. Maybe the ring disappeared because it was closely connected with Alan's problem? Maybe not, though, because the necklace was linked to the mom...I don't know.

I love the show, too. I plan to rewatch it soon and see what I can catch a second time through.