Japan You Want doesn't have any Saniro or Fantasy Meets in stock, despite having all the other versions. This likely means Bandai for whatever reason has discontinued them, likely due to Covid-19.
Maybe they’re just in short supply of those particular models (especially - as you mentioned - during a global pandemic)?
No stock doesn’t necessarily mean they’ve been discontinued. Is Japan You Want the only supplier of Sanrio / Fantasy Meets? Are they still being offered by other suppliers? Maybe it’s just a general shortage caused by Covid?
Amazon Japan also has the Sanrio Meets in stock for the standard retail price (sold directly by Amazon, not by third-party sellers), at the time of writing. They have 8 left, but don't have a restock date.
There's no reason for Bandai to discontinue popular and profitable models at a time when spending on toys and games is way up due to the pandemic, so my assumption is just that the pandemic has constrained supply.