I can confirm that the issue already started with iOS 17.x, as someone else already mentioned. I'm pretty sure that, for me, it started with iOS 17.6. I experienced delays with one of the HomePod pairs (HomePod 2gen) and had opened a case at my network manufacturer (Ubiquiti) for investigation. We optimised a couple of things but nothing improved the situation. I received a custom firmware for my U6 Pros and this solved the stereo pair delay, but with iOS 18 I had this static and crackling sound on exactly this pair. I also have it very rarely with a single HomePod 2gen.
What the Ubiquity support and I had discovered are:
1) Sometimes the HomePods showing an unexpected high latency for a couple of seconds. Like they are busy with something. This latency jumps happen independently from playing music, or not.
2) The 5GHz Wifi is offering a channel width of 40 MHz. But all the HomePods just using the 20MHz channel width. AppleTVs and all other devices using the 5GHz Wifi are using the 40MHz channel width. In case the HomePods are deciding by themselves to use 20MHz, then I have this static/crackling sound and audio delays. Sometimes, they are using the 40MHz channel width and from what I have experienced, then the issue is gone and the playback is rock solid. Unfortunately, I have found no way to force them to use the offered channel width and it happens rarely, that they are using it by themselves. So, no hard evidence on this.
I will try to set the channel width to 20MHz and check, how the HomePods are behaving.
I already have a case open at Apple and I can just encourage everyone to do the same. Probably you don't get a solution right at your hand, but just with cases we can bring up this topic to attention.
The first days the Apple support was very committed to the topic, but since the last days there is no response from them. If I don't receive any feedback, I will start an official escalation at Apple about this (living in Germany, so we have some options due to laws to support end-customers).