Minecraft 1.12.2
Mod version 5.2.101
Cosmos version 7.2.05
crash-2022-05-29_19.40.59-server.txt

Was running Single Player (Don't know if that qualifies a s server or client)
Brought the issue to BetterPortals page Johni0702/BetterPortals#616
"when visiting the pocket Dimension the view gets weird like I'm perpetual falling, all my equipment is gone, but when I get quit to menu and log back in everything is fine, I'm in the pocket dimension, all my gear is there, but when I leave same thing happens again"

Hope this helps.

Hi, the 1.12.2 version is End of Life, and as such will not be updated except for Critical Issues. If BetterPortals responds to you please let me know and I may be able to take a look into this.

The author has marked as waiting for third party Johni0702/BetterPortals#616