inoremap <M-i> <Up>
inoremap <M-k> <Down>
inoremap <M-j> <Left>
inoremap <M-l> <Right>
inoremap <M-u> <C-Left>
inoremap <M-o> <C-Right>
These mappings work perfectly with 8.1, They just move the cursor and don't change the text. To my surprise, If you press the arrow keys under the input mode, Then vim would interpret them as the escape-leading sequences and resulting in the text being changed.
Now with 8.2 vim would always interpret the arrow keys as the escape-leading sequences. I think if it's possible to avoid such behaviour with key mappings (like with 8.1), It surely would be preferable.
Probably wait for more reports. See if others have this issue as well.