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bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4
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it is not a recommendation to change the letter cases when turning them into QR code, it is an option that exists to server very special cases like if you wanted to print the address on a very small surface like a physical bitcoin otherwise it is best to stick to lower case because the other wallet that reads it may not be as sophisticated to recognize upper case!
When doing demos / discussions I tend to put everything in uppercase because of:
It tends to be a bit larger so you can read it better. Don't think about reading it on your PC screen, think about it in a youtube video or on a projected screen in the front of a room. Also I tend to use bogus / invalid addresses so nobody can copy / paste and send someplace they should not so it does mater as much in terms of invalid things.
I would not want to change any letter case ever. QR code or anything else, 10 or 15 years from now if some standard changes having to track down "wallet x" because it will read some changed data could be a nightmare.
-Dave