The tag alias #80844 thumbs -> thumb is pending approval.
Reason: Plural to singular. The plural tag in the post changes had 35 uses in the past 16 years.
Topic: Tag alias: thumbs -> thumb
Posted under Tag Alias and Implication Suggestions
The wiki page for thumb makes it seem like it should be a disambiguation or invalidated.
I'd suggest changing to category to Invalid as well (for the mod approving this).