This is called nominative fair use. But Redis's own guidelines for nominative fair use acknowledge that there are cases where you can "use the trademark in the name of your own product": https://redis-doc-test.readthedocs.io/en/latest/topics/trade...

>you may only name it "XYZ for Redis™"

However, I'm not sure where courts would land on a name like "redis-rs". There are arguments on both sides, and I'm not sure if there's enough case law to make the legal outcome clear.