Does anyone have any advice for sliding glass doors and retaining heat during the winter months.

Apartment, so I cannot attach anything adhesive or nails, which limits what I can do... lease explicitly prohibits...

@sentientdessert REALLY thick curtains* and a stuffed fabric "draught excluder" (pictured) is all I can suggest off the top of my head which wouldn't involve fixing anything directly to the doors.

*Thick curtains also help to keep a room cooler in the summertime.

@stueytheround @sentientdessert The problem is that it's likely the vertical edge that needs sealing. I've put this along the door's front edge:

https://www.amazon.com/gp/product/B07RWHYZGK/ref=ppx_yo_dt_b_search_asin_title

While it is adhesive, it'll peel cleanly off a metal surface without damage.

Depending on where you are in the country you may have renters rights to get the landlord to fix it.

@sfleetucker You're likely right, that's why I mentioned the curtains idea as I wasn't sure about adhesives. TBH if you can remove something and leave no trace when you leave, most landlords don't worry.
@sentientdessert

@stueytheround @sfleetucker @sentientdessert

Spackle is your friend. Tiny nail holes are easier to conceal than tape that rips up the pain finish.

If the paint is something other than white, you can find a good match with apps from paint companies. You take a picture, it tells you the closest color. With a tiny jar of that color and a jar of spackle, you can nail all you want.