US 2020 Election: 'Why am I seeing this ad' tool not appearing for some US-based users

On Election Day, there were some reports of Facebook users not seeing the "Why am I seeing this ad" information tab on political ads appearing on their newsfeeds.

Affected users were shown an error message stating "You can't use this feature right now. We limit how often you can post, comment or do other things in a given amount of time in order to help protect the community from spam. You can try again later. If you think this doesn't go against our Community Standards let us know".