The rate limit is in MB/s, so 10 is then 10 MB/s. This limit sits on the tap device and should work irrespective of the bridge.
https://192.168.16.45:8006/pve-docs/chapter-qm.html#qm_network_device
The rate is in MBps not Mbps. So if you write 60MBps it means 60*8=480MbpsI highly doubt this. If I set rate limit to 60, I get 500 Mbps....