It is actually terrifying how successful the cloud provider cartel has been at spreading FUD about SSPL. Denied OSI certification and packages getting dropped from repos?
Debian has an unusually strict policy that will absolutely err on the side of not including packages (famously not packaging things you need, like video drivers) and valkey is simply better than redis anyway (more features, better performance) and is drop-in compatible, so it was an easy choice for them.