I don't know the max bitrate Quest2 can handle, as my highest bitrate files have 80Mbps (which work totally fine) but it's important that you stay within the supported 8K resolution for hardware decoding of h265. For h264 the limit is 4K. Same for nVidia cards (since 10xx generation). Older AMD cards can't handle those files at all.
If you use a link cable with your Quest, the decoding is done by your PC, so in that case the max. bitrate of your link cable or Quest 2 doesn't matter at all. Transfers over link cable get reencoded, so you don't keep the bitrate of your source file anyway.
That's why Heresphere + SMB or Heresphere + XBVR are recommended for Quest 2 users. That way your files are decoded on your Quest 2 without the loss you would have through link cable.