I am seeing a lot of issues with the AO, it just is no where close to previous SSAO effects available for the built-in pipeline. Is it still early days? Image (basically standard HDRP from start with exaggerated AO):
HDRP uses GTAO as ambient occlusion algo which is in many ways more physically correct than the old SSAO in PPv2 but it has it’s own issues.
As for your issues, see this post: SSAO halos/bright-edges
yes oops I have repeated the edge issue, but how about the gap underneath floating objects - is that a standard problem with AO I didn’t notice?
The SSAO may be more physically correct but it just does not look good enough in gaps or is unbalanced across a scene so some obvious ceiling edges have none for example. Though to be fair I can not use baked shadow-maps so I need to rely on AO to fill some lighting gaps!
Have you experimented with the HDRP screen space AO quality settings?
At minimum radius and enough steps it is not bad (some slightly rough areas), a larger radius creates issues under floating/over-hanging objects