This update brought many new features and has been great so far, but there are a couple minor issues:

1) Tools in painting mode cannot be easily rearranged as they can't be dragged.
2) Dodge and burn settings in painting mode can't be changed because double tapping them yields no result, unlike Paint and Eraser. This is also true for every tool that wasn't there in version 2.2.x.
3) Let users add more than 9 tools in Painting Mode, as there's room for many more. It would also be amazing if you could add quick menu actions too (like Edit>Transform, View>Mirror and so on). This would make painting mode as feature-rich as Normal Mode.
4) HSL adjustment hue range customization is great, one of the best implementations I've seen, but as of now the sliders are a bit laggy.
5) The reference image floating window is also a fantastic addition but it would be even better if it could also fit color sliders or swatches in the form of tabs. It will be even cooler if it could also be zoomed in and out with gestures and snapped out of the canvas when not in use, similar to iOS' PIP box. Another great addition would be the ability to choose the reference image from files, as I don't personally like the iOS' gallery and store all my images within the Files app.

Lastly I have a question regarding future updates: Are smart filters, pen tool and vector shapes planned? Adding those features will let many people abandon Photoshop and it's abysmal subscription plan, and make Artstudio Pro one of the best professional photo editing and painting programs.

While in Edit>Transform>Scale mode it's pretty common to accidentally trigger a little rotation change (0.1 ~ 2°). Not a big deal, the real problem is that this action can't, for some reason, be undone without re-entering the Transform UI.
Since the difference is not that big, though, I can't honestly tell if the image actually rotates or if it just shows a wrong rotation value.

1) When you try to export a brush stamp using the 'Export selected item' feature, the app crashes.
2) If the HSL adjustment layer is set to 'Colorize' and saved, the popup appears shorter when 'Colorize' is set to off again.

The app won't let me delete documents (saved locally) but they can be deleted using Files.

Updated to 2.2.8 and tried to delete some documents (saved locally) but could not find the recently deleted folder anywhere. Not in ipad>artstudio, not in iOS' recently deleted files and neither in the "ipad" folder or anywhere else in the files app. Is that linked to the fact I'm on iOS beta?

I would like to suggest these features:
1) Ability to save custom canvas size presets and ability to delete existing ones that may not be used frequently.
2) Add math operations to the value editor. Examples: I want a color to have exactly half the current saturation so I just hit a /2 button in the value editor. I want a layer to move up by a certain amount of pixels (already possible but it would still be useful for multiple translations) -> I just add the amount I need without having to calculate it myself.
3) Display the value editor when tapping on Size and Flow, in order to input a specific value.
4) Add resolution, ppi and possibly color profile in the documents view alongside size.
5) Make the whole view more "iOS-like" by renaming files with a tap on their name, by adding drag and drop support and by adding long press menu support for actions like duplicating and deleting.
6) A trash can or a recently deleted folder would be much appreciated in my opinion because it happened a couple times that I had to delete more than a document but also selected (and deleted) one to keep by accident. Not that big of a deal if everything is backed up but I still see it being useful.
7) Being able to export more than one document at a time would also be an appreciated feature.

One of the latest updates improved view>mirror by using the screen center as pivot (nice one, really) but one thing that should be considered is adding mirrored thumbnails in the layers panel while the view is mirrored. This would be helpful when trying to erase accidental little strokes that make a layer "larger" than it should. To quickly identify those I usually look at the thumbnails but when in mirrored view this "trick" does not work of course. That would also be a bit better-looking since it's consistent with the actual view.

Not sure if it has already been suggested but the gradient in the gradient tool needs to be editable before applying. If it's just 2 colors trial and error is good enough but if you plan to use something precise (4 and up points) that's just unreasonable. The only way to make it work is to apply the gradient to an empty layer and then transform it to match the space it has to fill but this decreases the gradient quality due to interpolation.