Morgan Silver Dollar ... any thoughts on what this is?

I am going through my father's coin collection and this stuck out.  Could it be an error of some sort?

Just some residue from tape, unfortunately not unheard of as it kills the value

No it doesnt. Tape toning adds interest to an otherwise boring bullion coin.

Welcome to Numista.  Agreed, tape residue. That is a very common 1921 Morgan Dollar in excellent condition detail wise,  but to most collectors  the resulting uneven toning and blemishes caused by the tape detracts from it's eye appeal and desirability. You could try to soak it in acetone overnight which will not harm the coin to potentially remove the residue GENTLY with cotton swabs. Still no guarantee it will ever recover from what was done to your coin but it could improve it's overall eye appeal. 

you can buy buckets of UNC 21s for BV+/-. ,  why on earth would you try to make an eye catching artifact stop it and go back to look like everthing else in all the buckets?😜 ffs.

Mr. Midnight

you can buy buckets of UNC 21s for BV+/-. ,  why on earth would you try to make an eye catching artifact stop it and go back to look like everthing else in all the buckets?😜 ffs.

You have made it abundantly clear what appeals to you however the vast majority of collectors and the marketplace for them do not agree with your view of what is appealing. Why do you belabor the point of what appeals to you only? This is a coin in his possession and said nothing about purchasing one. Are you suggesting that this defect actually adds value? What is your point anyway other than what appeals only to you? You didn't even try to answer his inquiry. This is not about you. This is about addressing the OP's question. 

the original query was “is it an error?” I guess not. /thread.

The Morgan Silver Dollar is one of the most iconic and widely collected coins in U.S. history. Minted from 1878 to 1904 and again in 1921, it features Lady Liberty on the obverse and an eagle on the reverse. The value of a Morgan Silver Dollar depends on several factors, including its date, mint mark, and condition. Common dates may be worth around $30-$50, while rarer dates, like the 1893-S, can fetch thousands. For an accurate valuation, it’s best to have the coin professionally graded by a service like PCGS or NGC.😄

For more information, you can also visit Big Apple Coins