Icons for mini machines are different with each other. One is slightly smaller machine with double square, the other is same size machine with light blue L shape on all 4 corners.
Double square icons are noticeably shown in Bob's Mods.

Hm, I'm not entirely sure what you mean by "double square", but by default, without any other conflicting or interacting mods, the crafting menu should look something like this:

-with the blue corners as you described. The 2 at the beginning of the list are some new bobs assembly machines (steam and coal powered, I think?) and the 3 at the end are electronics-exclusive assembling machines; each unrelated to mini-machines.

If your issue is something else, then there might be another mod that is affecting the sprites. You can hover over the original bobs version to see what mods are listed in the yellow-text section, and if there is something overwriting bobs sprites, it will come after bobassembly in the list.

This is what I meant: https://imgur.com/3UC1T15
When I hover to that double square icons, mods that affect them are: Bob's Mods, Mini Machines, and Artisanal Reskin.
Those shows up when I use Bob's ones. They return to normal blue corner when, for example, I use Bobless Krastorio 2 playthrough some days ago.

By the way, how to insert picture directly to this discussion? Lol

Ahh, I see what you mean now; by default, the mini machines all copy the base machine icons, and then add the teal in the corners to mark the difference (with micro machines having purple to differentiate between the two). If you disable the "New Icon Handling" setting, then it will use these older icons that I manually edited to be smaller versions of the vanilla icons (which have not been updated, and likely all look different or lower quality than the current vanilla icons)

The Artisanal Reskin mod updates the mini machine icons to be the slightly smaller version of the machine (not sure if these are manual edits or done on the fly with code) with the double-square overlay in one corner, and the tiering bars in the other corner.

The inconsistency problem might be because Artisanal Reskin only affects mini machines that have more than one tier, so if you were missing bob-logistics in one modlist, then the mini-tank would not be reskinned, or if you were missing bob-mining in another modlist, then the mini-mining-drills would not be reskinned. I'm not sure if there's a way to disable Artisanal Reskins for just the mini machines, but there might be a setting for it.

Oh, and also to embed the image directly into the post, you would write the line like:

• ![Imgur] | (linktotheimage)

without the vertical line in between the square bracket and the parentheses; have fun with that lol

I see, so the difference is because Artisanal Reskin has its own mini machine icon to complement the tiering system.
That means it is more to Artisanal side, right?

Ooh, I turned my head before how to put image directly. Usually there is an option to do that below comment/response box. Save a ton. Thanks for the tips.

Yup, it would be something to fix on Artisanal's side.

I got the information about the image embedding thing from the Markdown formatting link that only appears when editing the description of a mod on the portal; I can imagine why most people haven't seen it lol