\Redis::flushDB sometimes returns false #2096

Expected behaviour

Always return true, as specified in Doc

Actual behaviour

Sometimes returns false

I'm seeing this behaviour on

• OS: Ubuntu 18.04.6 LTS
• Redis: 6.0.6
• PHP: 8.0.17
• phpredis: 6.0.0-dev

Steps to reproduce, backtrace or example script

I've checked

• There is no similar issue from other users
• Issue isn't fixed in develop branch