Congratulations. To me, it looks clean and free of a bunch of stuff I’d have to move to use it effectively for a week!
I think it’s perfect. Bright white towels always make me feel comfortable in their cleanliness.
Call it a win!

Other words for "boring" are classic, simple and enduring.

I think the room looks great /needs nothing, but if you want to do something, a pale blue or green paint on the walls might add personality.

I'd jazz it up a bit. A rug over the tub is needed to step on after bathing. If you don't have artwork on the wall across from the toilet - add something.

Some kind of soap dispenser on the countertop.

Might be needed?

Shampoo -etc...dispensers in the shower.

Stop while you are ahead. This is perfect for a rental. Easy to clean walls, enough space for people to place their own products. Clean, simple. It is inviting and looks well cared for. The mirror looks high end.

Theresa Peterson is correct!
This bath reads as clean and classic.
I might want to switch the art over the toilet to just one larger piece.
You are right to keep the "liftables" to a minimum( unfortunate reality of rental spaces).
A basic generic supply of cleaning products ,sponge wipes,toilet paper,soaps,shampoos should suffice.
Renters can supply their own exotic chi chi cosmetics.
Ask me how I know.

This bath is perfect. I believe when you say cold you are reacting to the color of the light being given off by your lighted mirror. Its color is in sharp contrast to the warm light you have mounted above your shower.

You might want to check to see if the mirror allows you to adjust the color of the light. Once you change that, the appearance of your bathroom should warm up.

It's a rental. Perfect as is. Clean and crisp is all you need (and easily cleanable).

First thought is to bring in artwork that has color and pattern.