1. The best team I've ever worked with considered every support request to be a bug. Is the user confused? At minimum, that's a documentation bug. It's also possible the product itself should be doing a better job stepping the user through a process or self-diagnosing.
As usual, "that should be easy to fix, just line of code here". At least from SWE perspective the fix may be easy to make but architecture or product management team may not be so happy about such pitch, especially when customer responds with "oh great, when?".
2. Not every bug is directly related to the product owner/team. Bugs can be introduced from different teams/processes.
3. Requiring senior engineers to do L1 and L2 support is likely a misallocstion of resources when less senior people can handle those issues.