The purpose of UBI as I understand it would be to provide a stable floor of income for people independent of employment. I think of it as being like a minimum wage - not high enough for a middle class standard of living, but hopefully higher than the poverty line. Enough to keep food on the table.
There are arguments that UBI is not attainable/sustainable, but that's different then getting the definition wrong
I think shelter, clothes, internet, and food would be a reasonable modern standard but that shelter doesn't have to mean a 3000 sq ft house, and internet doesn't mean they have the fastest connection speed possible in the area, and food doesn't mean steak and lobster every night.
That standard should increase as technology improves, for instance if we did this in the 90s having internet access would have been a luxury and not a requirement for being part of society, but it doesn't have to be something luxurious compared to the time period its paid out in
Then people would want to work to regain at least their previous standard of living.