Of course since the old syntax is merely deprecated and not removed, going forward you now have to know the old, bad form and the new, good form in order to read code. Backwards compatibility is a strength but also a one-way complexity ratchet.
At least they managed to kill `auto_ptr`.
If two template spellings trip you up, C++ is not your biggest problem. The joke is that each 'cleanup' sands off a tiny rough edge while the commitee leaves the old strata in place, so the language keeps accreting aliases and exceptions instead of dropping dead weight.
PyCuda 2024, used fairly often in certain industries, still contains `auto_ptr` ;-;
I think Rust has shown a way to remove deprecated interfaces while retaining back compat - automated tooling to migrate to the next version and give a few versions for a deprecated interfaces to stick around at the source level.