The GSMA royally fecked up the 5G protocols, just because you’ve got a 5G icon doesn't actually mean you have a 5G connection. It’s likely you were still connected to LTE, but the cell you were connected to is capable of 5G but it isn’t active.
The GSMA recently recommended that phones show a 5G icon even when they can't find 5G NR coverage. Thus, it's clear that the relative simplicity of today's mostly ubiquitous '4G LTE' status icon is not going to carry over into the 5G future.
Basically three 5G icon states should really still be 4G.