It's the same for t4g.
> T4g instances start in unlimited mode by default, giving users the ability to sustain high CPU performance over any desired time frame while keeping cost as low as possible. For most general purpose workloads, T4g instances in unlimited mode provide ample performance without any additional charges. If the average CPU utilization of a T4g instance is lower than the baseline over a 24-hour period, the hourly instance price automatically covers all interim spikes in usage. In the cases when a T4g instance needs to run at higher CPU utilization for a prolonged period, it can do so for a small additional charge of $0.04 per vCPU-hour. In standard mode, a T4g instance can burst until it uses up all of its earned credits. For more details on T4g credits, please see the EC2 documentation page.