Copy and paste string to Excel (android app) auto detect character class or formula class, I tried to copy and paste text to Googlesheet (android app) and excel (android app), googleapp (image on the right) will auto detect as character class, but excel (image on the left) in formula class shows an error.

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If you are not typing a formula, then you should not use = as the first character in Excel. If you are typing a formula, then make sure that you have typed it correctly. As stated here:

The #NAME? error signifies that something needs to be corrected in the syntax, so when you see the error in your formula, resolve it. Do not use any error-handling functions such as IFERROR to mask the error

To solve your issue, type a single quote ' before =, or replace the equal sign with a single quote. Excel will recognizes that you are not typing a formula and will show the value you entered.