Find the size and color of the tile, or close to it, and replace.

Could you move the tp holder over it ?

If the second toilet paper holder is removable, put a magazine holder toilet paper combo over the hole.

Is there a loose tile somewhere you can remove and take to a tile store? I doubt you can find an exact match, but something the closest possible color would look better than a hole in the wall.

I could remove the old toilet paper holder, but then I have 4 drill holes visible (although that isnt as bad as a missing tile I suppose). I like the idea of a magazine rack or something that I can play off in that spot. Looking online now to see what may work. Pictures are next week so I don't really have enough time to try and match the tile. Thank you all for the ideas and suggestions!

I know you are trying to find solutions, but a magazine rack isn't a good one. First of all, magazine holders in the bathroom are gross, and 2nd, actual paper magazines are a dying breed. I haven't bought a magazine in about a decade.

You could disguise 4 holes in the tile much easier than the missing tile.

You have a week to find the tile, we had to do this to ours in our last house when we removed handicap bars from our shower. It was an ivory tile just like that, we matched it no problem at lowes or HD. It was a few dollars.

Is that wood (the dark piece below the window)? Looks like a brace for a towel bar? If so, remove it, try to cut or pry one of the tiles out from behind it and use that.

A Chrome or stainless cover plate?

You mentioned your realtor, I would be concerned if my realtor did not have a contact who could fix your tile.

Ignore your agent - sell as is.

Not a Pro.

Is there a tile you can take from the back of your vanity? or anywhere else? behind mirror?

Not a Pro.

I don't know how this flew into my head and you may think I am a little crazy, but what about a Wall Mountable Sanitary Napkin Receptacle?

https://www.uline.com/Product/Detail/H-3454/Bathroom-Supplies/Wall-Mountable-Sanitary-Napkin-Receptacle-Stainless-Steel?pricode=WA9431&gadtype=pla&id=H-3454&gclid=EAIaIQobChMI_uafnaDx4wIVRWSGCh0BNgO0EAQYASABEgIBdfD_BwE&gclsrc=aw.ds

Eclectic Ware makes old-style ceramic wall fixtures:

https://www.eclectic-ware.com

I'm inclined to agree that it would be easier to hide the screw holes from the current TP holder, but I suspect they did that because the original location was too close to the toilet not to be in the way, which would also be a problem for anything else in that spot.

you bought it in that condition. Someone else will overlook that item also

Remove the tile even with the window. Paint the tileless wall the nearest color to the tile. Install a shelf under the window big enough for a plant or other thing. Shelf will sorta hide the missing tile...

Find a tile that’s close enough. Having a missing tile tells buyers it’s a “neglected house” and will turn them off. Do NOT leave it like this.

I agree with seeing if you can find a tile behind the vanity or somewhere else more hidden.

A tiny shelf for a smartphone.

That is definitely where an old tp holder was placed. It was probably set in there similar to a soap holder and, like many soap holders, eventually gave out leaving a hole.

find a black tp holder and put the tp there and use the current to as a little towel holder for the shower? it's stupid but at least it would be covered up. or put a towel bar over the black thing by the window and put a towel up.

You can hide the 4 holes by filling and then matching paint to cover. I did this for holes from grab bars and it worked very well, not perfect but not a big missing tile!!

My vote is with the suggestion to remove one from an inconspicuous place, use that to replace the one that is visible, get one to match as close as you can, to fill in the first one.

You have to replace 2 tiles. That hole is bigger that 1 tile, and the tile to the left of it is a partial tile. Steal 2 tiles from behind the toilet tank.

Obviously, go to the home center and/or tile store and try to match first. Take measurements and photos in good, bright light that accurately represent the color (unlike the one posted here).

You might try ebay-look for vintage yellow ceramic tile.
https://www.ebay.com/itm/4-1-4-Yellow-Tile-French-Vanilla-Daltile-Classic-Color-141-Vintage-Retro-Gloss/264391355753?hash=item3d8ef3ed69:g:jF4AAOSwZVJawptm:sc:USPSPriority!20191!US!-1

Smartphone toilet paper holder. Here's a double roll holder in case the single roll holder isn't wide enough to cover the hole: https://www.amazon.com/dp/B07D499Q9