Since halving, we can see that bitcoin fees and tx confirmation time has increased by 5 or 10X. So transactions with low fees took some weeks (really, I had one transaction that took 2 weeks to be confirmed).

It's partially because of, with halving, some miners stopped their (unprofitable) machines and reduced global hashrate, but difficulty adjustment only happens every 2 weeks, so for ~1 week, there was less hashrate but the same difficulty, and block time was around 15 minutes instead of 10.

The problem is that users didn't stop transferring bitcoins, and transactions that weren't processed were "stacked" in the mempool that grew up to 150MB.

Another problem is the "advertisement" gave by the halving, that attracted new users that bought some bitcoins. It's a good thing for bitcoin price but it contributed to overload (a bit more) network.