If you look at pictures of de-lidded 5000 series processors, such as this 5800X3D shown on Videocardz.com, you can see that the factory IHS sealant is indeed black and not always perfectly applied, meaning an uneven looking edge is not necessarily an indication that it has been delidded.
https://videocardz.com/newz/amd-ryzen-7-5800x3d-processor-with-3d-v-cache-has-been-delidded
65°C when gaming and 90°C in OCCT stress test are normal operating temperatures for this chip, even under a 240mm AIO, as is also mentioned in that article.
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT
Ryzen R7 5700G | B550 Gaming X | 2x8GB G.Skill 4000 | Radeon Vega 8 IGP
Ryzen R5 5600 | B550 Gaming Edge | 4x8GB G.Skill 3600 | Radeon RX 6800XT