Yes, welcome to AMD club. Nvidia uses edge temps for it's curves, when hotspot temp can be up to 20-25 degrees higher.
AMD have default curve in BIOS that also uses edge temp from what i know, but if you try to set it manually it will use junction temp as higher temperature to set fan speed. Iirc even if you set fan curve in something like MSI Afterburner it will use junction temp as well.
Tbh it isn't much of an issue, and allows to actually even more reduce fan speed for low loads when GPU temp is almost equal to junction temps. (Like 65/69 [edge/junction] vs 65/89)
On other side, personally have other type of issue when fan speed curve resets to default one every time after reboot. Yes, i can restore OC profile every time, but fact itself... Ngl, default curve works really good for me anyways.