Slashdot has reported:

Valve has released a Steam Client beta that moves its Linux client to 64-bit architecture and runs it within a containerized Steam Runtime environment. The beta also introduces Steam Achievement Sets, but fully 64-bit-only Linux installations remain unsupported. Valve has not confirmed when either change will reach the stable Linux release, so users on the regular client will continue with the existing architecture in the meantime.

The updated requirements call for Linux kernel 5.6 or newer and glibc 2.31 or newer. Systems must provide both 32-bit and 64-bit libraries and graphics drivers, including multilib support, for compatibility.

Achievement Sets let developers group achievements for base games, downloadable content and seasonal content. Players can finish individual sets while keeping their existing completion status if developers later add achievements. Valve has also changed the achievements page to show progress across the groups.

Both the 64-bit Linux client and Achievement Sets are available through the Steam Client Beta. Valve has not provided a date for their release to the stable version.