Climate problems aside (this is a bug that will hopefully be ironed out with a software update), rear door sunblinds were never standard - only part of an option pack for the pre-facelift model (Family pack IIRC) and to be fair all manufacturers change their standard and optional equipment with each trim level. Sometimes they drop or include certain features and raise or lower the costs. Some equipment as we know here, has been actually removed completely (glove box lighting, rear passenger central armrest cup holders, driver's side grab handle, etc.)
Generally speaking, there's a lesson here for some, as as I've seen so many people moaning about what is and is not included in trim levels - do your research and check standard trim levels against option packs. If there's a feature you want look at the brochure - simple - it will tell you what is and isn't standard.
Even the option packs change from year to year, so essential to double check the car has what you want before parting with your hard earned cash.
This isn't just a Citroen thing, it happens with all manufacturers.
Some early 2017 brochures didn't even mention the rear window sun shade - so was probably just included on some trim levels - but on the 2020 brochure it was part of the family pack as I mentioned:
It's also worth mentioning that they have a 'cop out' clause on their UK brochures:
All equipment described in this brochure represents the technology of Citroën C3 Aircross SUV. This brochure is based on an international version, therefore some images and specifications might not be representative of models sold in the UK. To know in detail equipment that is available as standard or optional, please refer to the Product Specification brochure or visit citroen.co.uk.