I have two older DDs with ASD.
It sounds like eating is a source of anxiety for her already.
If executive function and central coherence are challenges for her, choosing from a wide selection of possibilities to meet quite a loose set of criteria may be quite a daunting task.
Once she had planned the meal, making changes to those plans to meet needs that she might have previously forgotten about could be harder due to to her rigid thinking and the requirement for additional executive function.
Often someone with ASD won't realise why things that seem simple to others feel like such overwhelming and daunting tasks and that can have a huge impact on their self-esteem. Being criticised when you have made a big effort can therefore result in a meltdown type of situation in which logical thought and communication go out of the window. This can easily look like obstructive and selfish behaviour.
I agree that it is reasonable for her to help out more at the moment. it will probably also support her self-esteem, sleep pattern, etc too. Just think carefully about the tasks she is asked to do. Ask her to work with you to identify what she could do that doesn't place too much of a demand on her. A short, routine task daily might be better, like wiping over the bathroom sink mid-morning or unpacking the dishwasher. Those things don't change from day to day and don't require a huge amount of executive function (unless you have the sort of kitchen where you need to move ten things to fit one thing in a cupboard).
Making the task a short one that happens every day will make it more routine and therefore, once it is established, it should feel more manageable.
If she hasn't been diagnosed then I wouldn't make any "special needs" type allowances. She clearly functions perfectly well when she has things set up the way the she likes them!
This is one of the most ignorant comments I have seen on MN for quite a while.
A child who has ASD but does not have a diagnosis still has ASD!
Lots of people with ASD function as if they were NT in their own homes or their own bedrooms where everything is set up to meet their needs.
When you talk to her, keep calm and speak clearly. Don't make her guess what you are asking for. It's reasonable to say that the gaming needs to stop at midnight but don't say she has to stop gaming all night. If she has been stopping at 4.00am, she hasn't been gaming all night and being accused of it will feel unfair.
Give her time to understand the issues and process them. Ask her to come back with her ideas for what needs to change and how it could change tomorrow.
If you threaten to take away the computer, she migth react like you're threatening the take away her access to oxygen because that may well be how it feels. The gaming has a structure and a script that allows her to feel included and successful. Don't underestimate the importance of that to her mental well-being. She has lost the other parts of her life that provide that.
Lastly, whatever changes you decide (preferably together) to make, give her time to process the new routines before they are implemented.
It sounds like she thrived on a very structured life before lockdown in which almost everything she did was planned for her and there was a huge amount of routine, repetition and familiarity. She must feel like the rug has been pulled from under her already and is hanging on desperately to what still makes her feel safe. Be very careful about doing anything that makes those feelings worse.
Good luck for this afternoon x