Back in the day, I discovered I could i) print over IR to our office's HP laser printer from my Psion organiser, ii) print control codes from the built-in OPL language to change the display message on the printer. I would occassionaly send messages like "insert coin", "too much paper", "grammatical error", etc. when colleagues were printing.

Still had one on my previous phone - LG V20. Loved when people starter looking around confused when I started browsing the channels on the public TV on gas stations, waiting rooms, gym etc.

Put me down for another complainer about the lack of IR blaster. I used my Huawei P30 as a remote for 3 different TVs, two different office ACs, and a workshop radio regularly. I also used it a lot when doing tech support for family for basic stuff like ruling out the remote not working on an AC for example, or accessing TV setup menus you can't access with physical buttons on the TV and of course mums lost the remote again.

Wing night at the pub took on a whole new danger. The IR blaster was a total selling point for me on a few devices.

Redmi Note phones still have (or at least had) them.

I really miss it too. My wife loses the remote every 5 minutes.

Still have an ir blaster phone, they can tear this old phone out of my cold dead hands

I remember transferring files via IR. It was convenient.

My Xiaomi from 2020 has it

My Xiaomi still has one, but reviewers actually complained about that.

Smart home systems will replace that, and it's more secure for everyone involved.