Snapping to grid get's messed up after scaling down vertexes I've been reading about snapping to grid and hopefully I'm doing it right.

Switching form units to meter measurements and setting the grid scale accordingly. Turning on Snap during transform and Absolute grid alignment.

Everything seem's to work fine until I scale something down (I'm aware that I have to reset (apply) the scale when resizing my whole model), but the problem seems to come up when I want to work with vertexes.

First I'm selecting, let's say 2 vertexes of my plane, scaling them down and it's okay. But then when I try to scale them up again they are snapping to completely new grid that I somehow created. I don't see any options to reset the scale in Edit Mode, also it would be such a pain to do it every time.

Here's a GIF that I recorded, this will help you better understand better what I'm trying to achieve and what I do step by step:
https://i.imgur.com/xAww7zS.gifv
I think the issue comes from a misunderstanding of when increment snapping works.

Grid snapping only works for translation operations, scaling and rotation use value increment snapping not grid snapping, since rotations and scaling can't always be forced to coincide with the grid without some distortion.

The fact that your first scale does alight with the grid is a coincidence because the starting plane edge was exactly 2 units in length, and the end vertex were both grid aligned to start with.

That resulted in increment snapped values randomly being fractions of 2 units, which matching the grid cells by chance. When scaling up again, the edge will have a random different length, and fractions of that value will no longer necessarily align with the grid.

Bottom line, if you want grid aligned vertex use translations, or manually match them after using other transformation tools.