Why do you keep lowering the amount of shortcuts visible on the new tab page?
It used to be, before the update that made Firefox look like Chrome and for a few months after, that I could have 16 webpages pinned to the new tab page on my 1366x768 laptop. Then it got lowered to 12, then 8 (but now it adjusted to screen resolution so I could still have 16 on my 1080p desktop). This was still usable, but then the shortcuts started increasing in size on my desktop too. 3 months ago the number there was reduced to 12, and now, with the latest update, its down to 8. There was no mention of this in the changelogs.
Three questions: 1.) Why do you keep increasing the size of the shortcuts with every update, even on high resolution displays? 2.) At this rate, how long will it be before there's a shortcut as big as the webpage taking up my whole browser window? 8 is ridiculously low for a 24 inch display already. 3.) Is this to make the ads you show on "enhanced" mode bigger and more obnoxious? Because I don't use enhanced mode and I never will.
Please add an option to increase the amount of pinned webpages in the next update, the speeddial plugin that your new tab page originally replaced has this, and your new tab page, if I recall, used to. Just a slider going from 8-20 would be nice. Even when the amount of shortcuts was responsive to my screen resolution, it was still tolerable as long as the highest tier was 12 or 16, but now it looks like you've just made 8 the unchangeable default on everything.
Opaite Mbohovái (2)
Sorry, I haven't seen that it was constantly changing. I saw one big change with borders / margins that drove me to seek out an add-on to rein it in to an acceptable limit. Any chance you inadvertently changed the zoom factor for the new tab page? Changes to "Zoom" would be saved / remembered for the first new tab opened, but as I recall additional new tabs opened without the saved zoom level. IMO, it was barely acceptable to begin with and then it was changed & seemed to be all over the place.
Try using the New Tabs Tools extension. https://addons.mozilla.org/en-US/firefox/addon/new-tab-tools/ Has its own preferences for Rows & Columns which work - unlike the hidden prefs (in about:config) for Rows & Columns which after that big change weren't respected.
The tiles seem to change shape and size based on the aspect ratio of the window. It's very hard to figure out how that is calculated.
Anyway, if you "zoom out" by holding down the Ctrl key and tapping - once or twice, does that get the page to a good place?
So that Firefox can remember your zoom level on the page the next time you open it, you may need to turn off preloading the page using this setting:
(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.
(2) In the search box above the list, type or paste newtab and pause while the list is filtered
(3) Double-click the browser.newtab.preload preference to switch its value from true to false
After the change, if you have any "new tab" pages open, close them, and open a new one, change the zoom setting, and now it should be remembered.
If you do not want to reduce the zoom level, the extension mentioned by the-edmeister has a rich set of options for styling the page.