I've been using Tynker on mobile for a year or two now, and a little on PC. Over this time I have found many issues with Tynker. These apply to the mobile, IOS version of Tynker.
1. Deleting a variable by dragging it from the blocks menu then pressing no leaves an image of the variable
2. Having more than 4 clones can cause lots of lag even if the code they run is simple (there has to be a way to optimize this!)
3. Finding other projects is very difficult because the only categories are recent and featured, and theres no filter in the search engine, which is also very literal
4. Many blocks have somewhat vague descriptions, or lack one altogether
5. Some blocks only exist on PC, such as notify, but work on mobile
6. Some blocks do not work on mobile, such as any visual effect other than ghost
7. Dragging blocks to the left to delete them can leave a "shadow block" if it is also shown connecting to another script while being deleted
8. Projects that work and look fine on mobile dont work or look worse on PC. For example, tap equated to click on PC, but if touch down or mouse X/Y didnt work, and some text was not positioned properly
9. Copying actors from other projects should have an option to also bring over global variables
10. the moderation team has a "bad taste" in featured projects. Ive seen many projects that are complex and show off the person's coding ability, but on featured i see dress-ups and bad drawings
11. Importing images on mobile seems to downgrade their resolution so it can be almost unusable
12. Object hitboxes with physics are very basic, only circle and rectangle
13. Placing blocks inside of expandable if/else blocks with many if's becomes offset from the visual
14. Existence of the math blocks such as =, >, and <, even thought they exist in single math block
15. The buttons to delete or edit actors can be pressed through the coding interface
16. Audio cannot be imported to Tynker in any way
17. Using false if statements sometimes doesnt work properly (i dont have an example as it happened only once to me. i just used if/else instead. I think repeat until touch down? is false does not work)
18. Block to detect what platform (device) tynker is being run on, but no substitute blocks for tapping, tilting, and camera
19. Some properties of actors changed when the code is run persists after it is stopped
20. When UI sounds is off, music is still stopped on the device when connecting blocks
21. Code blocks are not run very fast, and often limits me from creating more complex scripts
22. There is no "backpack" that lets you bring code blocks or scripts between projects
23. Comments on mobile are blocks in the control/flow category and color, but on PC are white sticky notes that can be put anywhere. They also cut off with ... after a certain, short length
24. Drawing blocks lack font options, and italic and bold dont work. Looks and Drawing are kind of connected but confusing
25. Only some options for Say block with styles work
26. Using move to top/bottom layer blocks messes with actor layers in the code, moving them to ridiculous values sometimes
27. Similar to with physics, actor hitboxes for touching other actor is sometimes inaccurate compared to the actor
28. No eraser in Drawing blocks
That concludes my list for now. I hope that Tynker can improve some of these over time. I want to see it become a powerful coding tool for kids like Scratch. The graphics seem more refined on Tynker, and it has a mobile app, but these issues seriously hold it back.