I was placing some framed panels from Framedblocks and noticed if you hold one on a grass block you can see underground. Probably a mod issue more than a pack issue. Not sure.

Version 1.0.21b

Also works when trying to place 2 of them together

As far as I can tell from limited testing, this is caused by Oculus. I can however not reproduce this with grass, only happens with water, stained glass and similar translucent blocks for me.

I would appreciate it if you made an issue on my repository with more detail, specifically the exact graphics settings and, if in use, which shader you are using and with which settings. That would allow me to dig deeper into this, though I can't guarantee you that there is anything I can do about this.