redisson: Unable to acquire subscription lock

During relatively high load (~150-250 requests per minute), I often see this error

Caused by: org.redisson.client.RedisTimeoutException: Unable to acquire subscription lock after 3000ms. Increase 'subscriptionsPerConnection' and/or 'subscriptionConnectionPoolSize' parameters.
	at org.redisson.pubsub.PublishSubscribe.lambda$subscribe$2(PublishSubscribe.java:69)
	at io.netty.util.HashedWheelTimer$HashedWheelTimeout.run(HashedWheelTimer.java:715)
	at io.netty.util.concurrent.ImmediateExecutor.execute(ImmediateExecutor.java:34)
	at io.netty.util.HashedWheelTimer$HashedWheelTimeout.expire(HashedWheelTimer.java:703)
	at io.netty.util.HashedWheelTimer$HashedWheelBucket.expireTimeouts(HashedWheelTimer.java:790)
	at io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:503)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:833)

I doubled the subscriptionsPerConnection from 5 to 10, the subscriptionConnectionPoolSize from 50 to 100, and the connectionPoolSize from 64 to 128, but it doesn’t seem to have helped.

How can I go about diagnosing/debugging this? Do I need to just keep increasing these parameters till it works?

Redis version

6.x

Redisson version

3.16.8

Redisson configuration

config.useSingleServer().apply {
    path.toIntOrNull()?.also {
        database = it
    } ?: run {
        logger.warn { "Unable to parse database number: $path from redis configuration" }
    }
    
    subscriptionsPerConnection = 10
    subscriptionConnectionPoolSize = 100
    connectionPoolSize = 128
    timeout = 6000
}
config.nettyThreads = 64

I have also tried using Redisson versions 12.0, 13.0, 14.0, 15.0, 16.0 and 17.0 without luck.