I get these placeholders in some incoming emails and sometimes on the web. I recently D/L the entire MS Win 7 font collection, to be sure I wasn't missing any, but I still get these symbols occasionally.
Win7 Ult/ 3.40 GHZ Intel Core i5-3570K /ASRock mobo Z77 Pro4 /SSD/ EUFI MS 3400 MHZ/8 GB RAM; Win 7 Ult/Verizon FIOS wired network
Waterfox Classic/Chrome / Firefox 115esr
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"The medium is the message." - Marshall McLuhan