The following almost certainly contain ASCII art but we were not yet able to decode them. Puzzle solvers from the Internet, we need your help!
  • tx b4ba91b4892ff85a5eb18b85bc1fd744d9418b2a71f1dc130447893b9e1cab60, block 651974 (2020-10-09) The link yang.yiping.de/btc is dead with no archives, but the toplevel yang.yiping.de is an obituary to a Chinese lady called "Yang Yiping" (杨一平). The Bitcoin message is acknowledged on the website at:
    archiviert auf der BTC Blockchain TX b8e80f2bd1eac8c6db4dfb8b6cc9c8eb71133cbc1a0d32e6952c1a2818eecc8f
    She apparently lived in Germany as the website is bilingual German/Chinese, the text:
    Wir vermissen dich
    means:
    We miss you
    TODO decode properly. It is encoded as P2PKH keys (20 bytes at a timt) but also contains its own newlines and trailing spaces. Maybe a start:
              .-==-.
              `-==-
               |    |
               |    |
               |
          Yang, Yiping
         '~~~~~~~~~~~~~~~~~~'
         *-====-.    .-====-*
         *~~~~~~~~~~~~~~~~~~*
         .-====='    '=====-.
         .~~~~~~~~~~~~~~~~~~.
         //yang.yiping.de/btc
         Wir vermissen dich! |
              Yang, Yiping   |~
    Could it be across? She's apparently Christian based on the website.
    tx b8e80f2bd1eac8c6db4dfb8b6cc9c8eb71133cbc1a0d32e6952c1a2818eecc8f, block 652005 (2020-10-09) also contains some related content with her name, though not identical. Perhaps they are meant to be assembled together somehow?
  • tx 71d9187cbb7b00b4c516df218499bbc301996262cfafc4533fd7916af1fb6315, block 709632, (2021-11-14 ) starts a consecutive sequence of transactions that seem to encode an ASCII art. Each line is encoded with OP_RETURN, is 38 bytes long, and starts and ends in 6 spaces, leading to 26 non-whitespace characters per line. In block order we have:
          ;4Fdzw1k=zzzzzzzzzzzzzzzz;      
          ,zzzzzq;.           1zzzz,      
          ,zzzzq  ,qzzzzzz1,  1zzzz,      
           ,;qzzzzz1qq,                   
                 ,;1zzzzzqqq,             
          ,zzzzq    .;qzzzzzq:1zzzz,      
          ,zzzzq:1zzzzzq;.    1zzzz,      
          ,zzzzq         .;qzzzzzzz,      
          ,vtv3f5aKY0jGQglP9a1AGw==.      
          ;BynQtpeUyWTXKGTrGhdV2Q==;      
          ;tVMd3L1CKM4wFmyxEEEUV2bY;      
          ,zzzzzzzzzzzzzzzzzzzzzzzz,      
          ,zzzzzzzzq,         1zzzz,      
                    .:qqzzzzqqq,          
          ,zzzzq       ,qzzzzzzzzzz,      
          ,zzzzzzzzzzzzzzzzzzzzzzzz,      
    The strings:
    vtv3f5aKY0jGQglP9a1AGw==
    BynQtpeUyWTXKGTrGhdV2Q==
    tVMd3L1CKM4wFmyxEEEUV2bY
    4Fdzw1k=
    seem like Base64 encoded data due to the = sign padding, but nothing human readable comes out of them.