In terms of "renewables", I'd love there to be a couple of spare toilet rolls for each toilet on arrival, even a half used roll each of kitchen towel, tin foil, cling film, grease proof paper.
In the bathroom, either a refillable container or a supermarket one, but if there was either a half full bottle of hand soap or a fresh bar in each bathroom, and a liquid soap beside the sink, that would be great.
If there is any kind of coffee maker, having at least a couple of servings initially would be great and knowing in advance what type means I could bring what I need (nespresso pods, other pods, grounds and filters for a pot, grounds for a plunger, ....).
In the kitchen, a few have had partially used salt and pepper, cooking oil, sugar, teabags, jar instant coffee etc. I have tended not to use these, but occasionally they've been useful. Some wash up liquid is great, and if there is a dishwasher and/or washing machine, a small amount of tablets/powder for those would be great.
Some have left a few things on arrival - bottle of wine, small pack of butter, jar of jam, home baked cake or nice loaf crusty bread etc, sometimes a bottle of milk and maybe a packet of rashers and mushrooms or eggs in the fridge. (Usually 3-4 bits max, only 1 was most of those).
I have a 4l box from IKEA that is my self catering box (and now camping too), built on years of SC holidays and their failures. It's a mix of tools I really miss if they're not there, and consumables that we tend to use on holidays (often they get in there by being bought on holidays and I throw the leftovers in the box for next trips as I have what I need generally in the kitchen at home). It has:
A tea towel, hand towel, 2 j cloths
A new pot scrubber (to be left behind/thrown out on departure), wash up brush, and 100ml squeezy bottle of wash up liquid.
9 dishwasher tablets (for a week visit) and enough washing powder for 3 washes (it was 2 double tablet packs, next time will have to be 3 capsules), in a ziplock bag
2 silicon hand mitts (for,lifting hot pots/trays)
Matches and 2 firefighters and a handful of nightlights (only ever lit on something to contain them safely)
Wooden spoon (short), sharp knife, peeler, can opener, corkscrew, IKEA non-stick set of (spoon, ladle, whisk, spatula, slotted spoon), tongs, handful of clippers (to seal bags)
Bin bags, couple of bin liners for small bins, part used box of ziploc bags (lots of different uses!!), part used box of ice cube bags (often there isn't an ice tray)
250ml bottle of olive oil, salt and pepper, couple of our favourite seasonings.
Part used pack of bamboo skewers (for bbqs or oven use)
Part used roll of tin foil, part used roll of parchment paper (there's usually cling film there, ziplocks cover most things I'd need cling for, but if I do end up buying 1 partway through, it will be stuck into the box)
Coffee filters
Handful of sugar "straws" and any other sachets I've gathered (ketchup, Mayo, vinegar, mustard) that might be useful
I have