"Oh no, I can't play this modern video file using a codec that's literally been around for more than 10 years unless you pay me $0.99 for a codec pack..."
Every single time I forget to change it and I want to play an h265 file from my phone.
H.264 had a license fee, but it wasn't ridiculous. It was jacked up for 265, to the point that a lot of software houses no longer bundle the 265 decoder license.
It annoys me too: Security cameras often use turnkey H.265 encoding packages rather than more open codecs, which makes dealing with the files using FOSS more of a pita.