Regular Expression-WeChat nickname contains special characters, causing an error in exporting phpExcel to excel

The database stores 8 J + Si + mrmOiPsuiPsvCfkos with base64_encode, and writes base64_decode to the excel file. The program has not encountered any problems before. This time, the data cannot be written to the excel file, when opening the excel file, the system prompts "** unreadable content found ". Are these special...

The value stored in the database is base64_encode.8J + Si + mrmOiPsuiPsvCfkos =, Base64_decode is performed when the excel file is written. There was no problem in the program before. This time, the excel file cannot be written. When opening the excel file, the system prompts "** unreadable content found ".
Should I replace these special characters or set the format in phpExcel? How can this problem be solved?

Similar to this problem:
Http://segmentfault.com/q/1010000002594934

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The value stored in the database is base64_encode.8J + Si + mrmOiPsuiPsvCfkos =, Base64_decode is performed when the excel file is written. There was no problem in the program before. This time, the excel file cannot be written. When opening the excel file, the system prompts "** unreadable content found ".
Should I replace these special characters or set the format in phpExcel? How can this problem be solved?

Similar to this problem:
Http://segmentfault.com/q/1010000002594934

Does the name contain emoji?