Stop lying. This is FUD. It must be disregarded with extreme prejudice. It is completely, factually, unequivocally, incorrect.
You can connect to Redis using their first-party, MIT-licensed client library. You can write proprietary software using that library with no requirement whatsoever to release your software under any particular license (although of course you still have to comply with the MIT license's attribution requirements). Heck, you can even serve this software to your users. The only condition being that you you distribute the original source or your modified changes of the AGPL'd part of the software in your stack to your users under the terms of the AGPL license. Nobody said you have to open up your whole stack. That's SSPL territory.