I have the exact same issue running MBP M1P Sequoia 15.2 and Safari 18.2.
NBA League Pass ticket number - 2630495
I have performed all the recommended troubleshooting steps as per NBA League Pass Support and as others have stated nothing has resolved it.
The final recommendation from NBA LP Support is to perform a factory reset on my MBP, however I haven't had the time to try this yet.
For context I have tried the following browsers:
- Chrome
- Firefox
- Edge and Edge beta
- Opera
- Brave
None of them have the CPU usage spike, however, they are not considered "secure" browsers by NBA LP and therefore only stream live games in a max of 720p. Games look absolute trash on a 1440p 27" monitor. This is not acceptable in this day and age as far as I'm concerned. Especially given the cost of LP.
NBA LP have essentially said they won't investigate any further as they cannot reproduce the issue on their end and have closed the support ticket.