It was somewhere outside Barstow when "Dave Plowman (News)"
wrote:

they're done like that to make warping unlikely.

This is Ikea - they're done like that to make them out of narrow
strips, rather than expensive wide timber.

A "chest top" would have been made from glued-up strips any time since
the 18th century, largely for stability. Pre-war though, you're
talking talking about two 9" wide planks, nowadays it's nine 2"
planks.

I'd bludgeon it flat by adding extra fastenings. I wouldn't steam it,
because any finish that permits steam through it isn't going to be
improved by the experience.

If you want good furniture, don't buy it from Ikea. Their timber is of
appaling quality, as you've just discovered.
--
Smert' spamionam