This made me curious about the long-term fee development: let's check the data...
As a rough estimate from this graph, I'd say transaction fees per block (measured in dollars, not Bitcoin) have been slowly increasing since the beginning because of the increase in Bitcoin value.
That's also what I said. Block subsidy aside, miners are earning less BTC/sats than they used to. Even before 0.1 sat/vByte became the new standard, there was very little congestion on the Bitcoin blockchain despite BTC hitting new ATHs several times. On top of that, the block subsidy has been halved a couple of times already. However, those sats are worth more in USD or any other fiat terms. It would be interesting to see a comparison against gold.
Btw, does this graph go all the way back to the beginnings of Bitcoin in 2009?