Well, that's really interesting. Did y'all edit the save though? Or did this happen on its own?
As I was able to reproduce this with save editing. It looks like the game will accept any positive number for the "trashCanLevel".
Example:
So a quick save edit to the following:
<trashCanLevel>59664</trashCanLevel>
Will end up giving a brand new, singleplayer file with default profit margins: $41347156
If you try to throw away 28 Gold Star Kale.
And, the trash icon will be missing.
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The trash can level should only be one of the following values: [0,1,2,3,4]
0 being the default, and 4 being the highest upgraded.
See the various versions of the trash can as noted by the wiki:
https://stardewvalleywiki.com/Trash_Cans
Oh, and let me know if you need help fixing the save.