Engine valve cover replacement due to oil leak followed by new, seemingly unrelated, symptoms

A couple of days ago my Chevy Cruze 2013, ~85k miles, had its engine valve cover replaced and 2 cam adjuster magnets resealed, according to the paperwork, due to an oil leak at the top of the engine.

The next day it was quite warm (I live in Sunnyvale, CA) and was driving with the air conditioner on. I stopped briefly then continued at very low speed, and I sensed an unusual vibration for a few seconds, which felt like an unstable idle, but looking at the rpm, it seemed stable around 900-100. It happened again maybe a couple more times while stopping and going at low speed, then I continued driving normally and didn’t sense this anymore. I didn’t try to reproduce it though in the same conditions.

BTW, idle is now at between 800-900 RPM, not sure if this is the normal value but I seem to recall that it used to be slightly lower, but I may be mistaken.

The next day I drove about 20 miles on the freeway and didn’t notice anything unusual. When I got back on surface streets, I noticed that each time I would stop then start at a light or stop sign, I would hear a relatively faint but distinct periodic clicking noise that seemed to come from the left front side. The frequency seemed to be somewhat correlated with the RPM, although at times it seemed relatively constant. As the RPM increased, the clicking seemed to disappear, although it may have been drowned out by the louder engine noise. That behavior continued for the rest of the trip. The clicking happened only when pressing the throttle pedal, there was no clicking at idle.

During this entire trip the air conditioner was on, and at some point I noticed that the air wasn’t as cold as before, and that the windshield was getting slightly foggy, and realized that while the fan was on, the air coming from the vents was warmer than usual. I pressed and depressed the AC switch a few times and the air temperature didn’t seem to change, indicating that the AC wasn’t working properly anymore.

I’m not knowledgeable enough to say whether there can be any connection between all these facts, but given that I have had this car for 8 years and never had any issues with it, and that the symptoms appeared right after the repair, it seems logical that they must be somehow related, maybe not directly, but possibly due to some accidental damage to something causing the new symptoms.

I would appreciate any insight.