Domains can be reclaimed by the owners. In fact, even if google let it lapse for some time they could still get it back because it is clearly a domain that goes with their brand. Others that have never owned a domain have been able to take them over because they belong to their brand.
What I haven't quite worked out in this case is whether the domain was ever truly available publicly. The domain was offered via the google domains registrar - it could just be that there was a coding issue on the site that allowed the domain to be made available despite it not actually being so.
In general domains that are brand based pretty much belong to the brand if they choose to take them up. See this news story