Hopefully an update that will allow Dota 2 to continue working on Linux and the Steam Deck long into the future.
Back in September 2021, Valve announced some major technical changes were planned for the Dota 2 client. This included dropping OpenGL support, with Vulkan as the default amongst other adjustments. Part of their plan has now shipped, at least for Linux.
At the bottom of their latest blog post, they noted that "As part of our continuing efforts to move Dota's technology forward, we have upgraded the Linux client to use the container version of the Steam runtime. This ensures better compatibility across distributions and prepares for future improvements.".
What is the newer container version of the Steam runtime? This was actually announced back in November 2019, with the idea to better separate games from your system. It should mean better and continuing compatibility across many different Linux distributions, without dependency headaches. It's the same system that Steam Play Proton also uses.
Really, you shouldn't see much difference. If you didn't see issues before, you likely won't now. If you did have issues before, it's worth checking it out again.