España Coin Error?

This comes from a "1975" una peseta (Juan Carlos I portrait on obverse) coin. As with most Spanish coins, the true date of issue is found in two tiny stars on the reverse. In this case, I think the true date is 1980, but it seems to be worn off. However, looking at the rest of the coin's reverse, there is very little wear on the coin overall.

So, my question is: Do you think this could be some kind of mint error? There are so far no reports of any kind of error like this existing in this series, so I'm not sure.

There was most likely some grease in the die when the coin was struck.

Like this:

Is there any extra value to a coin like this, or any added rarity?

Indeed, worth less. You can buy this coin in UNC grade for 0,50€.

https://en.numista.com/catalogue/pieces787.html

You can read a figure 8 in the star and this coin was minted only in 1980 in the eighties, so your coin is from that year.

No extra value or rarity since it's not an actual error. I usually spend coins like that since they're so common. The only reason I keep the quarter is because it's a nice conversation piece.

Hi from Spain.
This is very common in all coins with "Stars" (System used in Spain since late 1800's until 1982). Think about the low relief of the year written in the star. I've seen lots of completely uncirculated coins with deleted stars. The first coins strucks always are perfect but while the stamp is going wasted, the numbers appears more deleted.

And about value, usually here, these coins with star deleted are less valued than visible ones, think that sometimes it is not possible to know the real year of the coin (all value lost).

Regards.

Thank you all so much for the info and the help with this! I love learning new things about coins!

Regards,
Harlan