Edit: answered my own question here by downloading MonitorControl, works perfectly.
I rolled the dice on Ebay and got a brand-new, unopened 21.5-inch LG UltraFine last August. Despite being canceled two years earlier, I somehow managed to get this technological leprechaun for half the original MSRP, ~$350. I suppose somebody had it hidden under their bed and forgot about it. I'm babying it, because there are no affordable ~220ppi standalone monitors on the market. Currently, it's either the Apple Studio Display, the 27-inch UltraFine, or the Pro Display XDR. I suppose "affordable" is relative, when compared to the XDR.
I did run into one truly annoying problem with the UltraFine: the brightness would randomly reset after waking from sleep. I've had this problem since getting the monitor. I was concerned that the LG was showing signs of intermittent failure, and have no warranty coverage, obviously. Assuming this could be fixed, the cost of sending it to LG for repair wouldn't be worth it, even if they had a stellar reputation in customer service, which they clearly do not. They'd probably send the power cable back but forget the panel.
I spent many months like this, the brightness constantly resetting, and then having to go into Displays preferences to guess where I had it previously. I finally managed to diagnose the issue, and it turns out that this problem only happens when I have the UltraFine daisy chained with my BlackMagic RX 580 eGPU and 2018 Intel Mac mini. My Mac is held together with sticks and bubble gum, composed of various cobbled together upgrades, so I expected issues, but this was truly maddening; randomly being blinded after my computer wakes up.
I held onto Mojave until security patches ran dry, so this has been an issue ever since I purchased this unicorn off of Ebay. Eventually, I upgraded to Monetary, but the problem persisted. I didn't want to stop using the eGPU, nor did I want to upgrade to an Apple Silicon Mac just yet, but I was leaning toward getting a Mac Studio (I was hoping to wait for the M3 variant) because of how irritating this is, which isn't obvious until you have to deal with it on a daily basis.
While searching for a solution, I ran into this small utility called "MonitorControl". I thought I had found the answer, with the ability to default to the previous brightness settings. Unfortunately, none of those settings would stick, thus this issue remained unresolved. However, unlike Apple's brightness settings in Displays preferences, MonitorControl allows you to set a specific percentage in brightness, whereas it's all guesswork in resetting it through macOS. While I never found a solution for the brightness reseting, I figured out that I could easily use MonitorControl in the menu bar to set it to my preferred brightness, specifically 41% for my sensitive eyes. This was like mana from the gods, now that I no longer had to deal with this vexing issue.
Still, sometimes things turn right side up, and appear to fix themselves. Apple had serious performance issues with AMD drivers, specifically plaguing the 5000 and 6000-series of GPUs with the release of macOS 12.3. Using an older RX 580 based upon the Polaris architecture, my eGPU didn't suffer from the performance degradations. However, Apple must have mucked around with the entirety of the Radeon driver stack, because not only did they resolve the performance issues with the latest AMD GPUs, but with the release of Monterey 12.4, the brightness issue that had afflicted my Mac as early as Mojave was suddenly gone. Nary a brightness reset has happened since.
I don't know if Apple specifically fixed this problem, or if it was resolved due to happenstance with other changes in the drivers and/or firmware, but I'm quite glad to have it resolved. It also means that my LG UltraFine is not damaged or malfunctioning, so I can continue to use it without having to pony up for a substantially more expensive monitor. For the first time since I put together my "sticks and bubble gum" Mac mini in 2018, it's working at 100% functionality, so I don't want to upgrade right now, regardless.
The whole point of this long-winded journey of a post is to point out that small utilities like MonitorControl can be a digital lifesaver. Heroic unsung developers can fill in edge-case potholes, allowing the user to work around bugs that would otherwise cause serious issues; in my case losing sanity due to random brightness resets. I used MonitorControl for about six months, until Apple fixed the problem (intentionally or otherwise), and even though MonitorControl didn't completely resolve the issue, it made it tolerable. Now, with the issue finally resolved, I can keep my LG monitor with my current Intel Mac mini, and don't have to worry about being committed to a psychiatric ward because my mental faculties could no longer tolerate random momentary blindness. Assuming my LG UltraFine continues to function properly, I'll be able to use it with a future Apple Silicon Mac purchase, instead of selling part of my liver for a new "Retina" class monitor.
So, even though I no longer require MonitorControl, it was a massive help when I most needed it, and I am thankful for its utility, as well as keeping my sanity intact.