Looks like the Pixel 4a 5G is about to be discontinued
Apparently, the phone is no longer available on contract in the UK and in the US, it has vanished from Amazon and Best Buy. B&H Photo and Video explicitly says that the phone has been discontinued.
With the exception of Verizon, all major carriers still have the handset but it appears that US Cellular is about to run out. The phone is still available on Google Store.
Although Pixel 4a 5G's disappearance from digital shelves in no way confirms that the phone will be discontinued soon, it does seem to be the case, given that Google will supposedly introduce its successor, the Pixel 5a, in late July or August.
If a report from last year is any indication, Google didn't really have high hopes for its last year's lineup to begin with and had only planned to manufacture 3 million units combined of the Pixel 4a, Pixel 4a 5G, and Pixel 5 in 2020. That's not to say the Pixel 4a 5G is an underwhelming device. On the contrary, it's one of the best 5G phones around.
Although we don't know what the company's production plans were for this year, chip shortages may have had a role to play. Reports do indicate that Google has been affected and it's also allegedly the reason why the Pixel 5a will only be released in two markets.
Add to this reports that claim the Pixel 5a will essentially be a repackaged Pixel 4a 5G and it's not hard to see why Google could be planning to discontinue the phone relatively early in the life cycle. The phone came out in November 2020.