Well the infrastructure is getting better on the one hand, but the main reason that people lost interest. Once the price crashed from $20K to $9K, a lot of people lost interest, cut their losses and sold off their coins, so there are fewer transactions right now. Let's see what will happen once the price starts rising again and reaches, say, the $15K level.
It's mostly this, to be honest.
If there was still an insane amount of coins being pushed around by people trying to get into, around or out of exchanges, then the entire blockchain would be backlogged with a much larger mempool queue. It was also due to a ton of new people trying to get in on the entire thing, FOMO was becoming a normal thing for the average person and that was the big push for the entire system. Now that people aren't as interested, it is sliding down and the transaction queue will slide down with it.