My old lady is acting a little odd.

I have an older cat who has recently been doing some stranger things.

For about 2 weeks, she kept sitting in the same spot upright, staring at the wall. And frequently choosing to relax in the litter tray. (Sometimes on top of poop if it hasn’t been scooped in time) Sleeping in the bathtub

For the rest of the time she is her same old self. Obsessed with my partner, vocal for his attention, hissing at her brother :D and so forth.

Just these new behaviours I’m not used to and wondering if it’s part cats getting older or maybe a vet trip.