How powerful is lvl 100 glyph compared to 45? Any point of grind them?

I’m pretty sure the base glyph affect scales linearly. So a level 100 is 2.1x stronger than a level 46.

If your goal is to push pits then you’ll definitely notice a difference the higher you climb. If just playing normal content, don’t worry about it. Glyphs around 70/80 will easily destroy all content in game.